* [dpdk-dev] [RFC PATCH] eal: rte_rand yields only 62 random bits @ 2015-03-17 16:18 Robert Sanford 2015-03-27 16:38 ` Sanford, Robert 0 siblings, 1 reply; 9+ messages in thread From: Robert Sanford @ 2015-03-17 16:18 UTC (permalink / raw) To: David.Marchand, Bruce.Richardson, dev The implementation of rte_rand() returns only 62 bits of pseudo-randomness, because the underlying calls to lrand48() "return non-negative long integers uniformly distributed between 0 and 2^31." We have written a potential fix, but before we spend more time testing and refining it, I wanted to check with you guys. We switched to using the reentrant versions of [ls]rand48, and maintain per-lcore state. We need ~2.06 calls to lrand48_r(), per call to rte_rand(). Do you agree with the approach we've taken in this patch? Thanks, Robert --- lib/librte_eal/common/include/rte_random.h | 33 +++++++++++++++++++++++++-- lib/librte_eal/linuxapp/eal/eal_thread.c | 7 ++++++ 2 files changed, 37 insertions(+), 3 deletions(-) diff --git a/lib/librte_eal/common/include/rte_random.h b/lib/librte_eal/common/include/rte_random.h index 24ae836..b9248cd 100644 --- a/lib/librte_eal/common/include/rte_random.h +++ b/lib/librte_eal/common/include/rte_random.h @@ -46,6 +46,17 @@ extern "C" { #include <stdint.h> #include <stdlib.h> +#include <rte_per_lcore.h> +#include <rte_branch_prediction.h> + +struct rte_rand_data { + struct drand48_data _dr48; + uint32_t _hi_bits; + uint8_t _bits_left; +}; + +RTE_DECLARE_PER_LCORE(struct rte_rand_data, _rand_data); + /** * Seed the pseudo-random generator. @@ -60,7 +71,7 @@ extern "C" { static inline void rte_srand(uint64_t seedval) { - srand48((long unsigned int)seedval); + srand48_r((long unsigned int)seedval, &RTE_PER_LCORE(_rand_data)._dr48); } /** @@ -76,10 +87,26 @@ rte_srand(uint64_t seedval) static inline uint64_t rte_rand(void) { + struct rte_rand_data *rd = &RTE_PER_LCORE(_rand_data); uint64_t val; - val = lrand48(); + uint32_t hi_bits; + long int result; + + if (unlikely(rd->_bits_left < 2)) { + lrand48_r(&rd->_dr48, &result); + rd->_hi_bits |= (uint32_t)result << (1 - rd->_bits_left); + rd->_bits_left += 31; + } + + hi_bits = rd->_hi_bits; + lrand48_r(&rd->_dr48, &result); + val = (uint32_t)result | (hi_bits & 0x8000000); val <<= 32; - val += lrand48(); + hi_bits <<= 1; + lrand48_r(&rd->_dr48, &result); + val |= (uint32_t)result | (hi_bits & 0x8000000); + rd->_hi_bits = hi_bits << 1; + rd->_bits_left -= 2; return val; } diff --git a/lib/librte_eal/linuxapp/eal/eal_thread.c b/lib/librte_eal/linuxapp/eal/eal_thread.c index 5635c7d..08e7f72 100644 --- a/lib/librte_eal/linuxapp/eal/eal_thread.c +++ b/lib/librte_eal/linuxapp/eal/eal_thread.c @@ -52,6 +52,8 @@ #include <rte_eal.h> #include <rte_per_lcore.h> #include <rte_lcore.h> +#include <rte_cycles.h> +#include <rte_random.h> #include "eal_private.h" #include "eal_thread.h" @@ -59,6 +61,8 @@ RTE_DEFINE_PER_LCORE(unsigned, _lcore_id) = LCORE_ID_ANY; RTE_DEFINE_PER_LCORE(unsigned, _socket_id) = (unsigned)SOCKET_ID_ANY; RTE_DEFINE_PER_LCORE(rte_cpuset_t, _cpuset); +RTE_DEFINE_PER_LCORE(struct rte_rand_data, _rand_data); + /* * Send a message to a slave lcore identified by slave_id to call a @@ -147,6 +151,9 @@ eal_thread_loop(__attribute__((unused)) void *arg) /* set the lcore ID in per-lcore memory area */ RTE_PER_LCORE(_lcore_id) = lcore_id; + /* seed per-lcore PRNG */ + rte_srand(rte_rdtsc()); + /* set CPU affinity */ if (eal_thread_set_affinity() < 0) rte_panic("cannot set affinity\n"); -- 1.7.1 ^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [dpdk-dev] [RFC PATCH] eal: rte_rand yields only 62 random bits 2015-03-17 16:18 [dpdk-dev] [RFC PATCH] eal: rte_rand yields only 62 random bits Robert Sanford @ 2015-03-27 16:38 ` Sanford, Robert 2015-03-28 0:02 ` Stephen Hemminger 2015-03-28 0:03 ` Stephen Hemminger 0 siblings, 2 replies; 9+ messages in thread From: Sanford, Robert @ 2015-03-27 16:38 UTC (permalink / raw) To: dev, David.Marchand, Bruce.Richardson Never mind ... I cancel the previous suggestion. After further reading on RNGs, I believe we should abandon the use of lrand48() and implement our own RNG based on the so-called KISS family of RNGs originally proposed by the late George Marsaglia. In his excellent paper, "Good Practice in (Pseudo) Random Number Generation for Bioinformatics Applications", David Jones (UCL Bioinformatics Group) describes a few variants of KISS generators. This paper, and Robert G. Brown's (Duke Univ.) comprehensive "Dieharder" random number test suite work show that KISS RNGs are simple and fast, yet high quality. Something like JLKISS64(), with state kept in TLS, would be ideal for DPDK use. In limited experiments, I found JLKISS64() (not inlined, compiles to ~40 instructions) to be ~4 times faster than rte_rand(). This is probably because JLKISS64() achieves integer-instruction parallelism, while rte_rand(), with its two calls to lrand48(), nrand48_r(), and __drand48_iterate(), does not (and all those calls!). Here is the JLKISS64() function, as it appears in Jones's GoodPracticeRNG paper: --- /* Public domain code for JLKISS64 RNG - long period KISS RNG producing 64-bit results */ unsigned long long x = 123456789123ULL,y = 987654321987ULL; /* Seed variables */ unsigned int z1 = 43219876, c1 = 6543217, z2 = 21987643, c2 = 1732654; /* Seed variables */ unsigned long long JLKISS64() { unsigned long long t; x = 1490024343005336237ULL * x + 123456789; y ^= y << 21; y ^= y >> 17; y ^= y << 30; /* Do not set y=0! */ t = 4294584393ULL * z1 + c1; c1 = t >> 32; z1 = t; t = 4246477509ULL * z2 + c2; c2 = t >> 32; z2 = t; return x + y + z1 + ((unsigned long long)z2 << 32); /* Return 64-bit result */ } -- Regards, Robert >The implementation of rte_rand() returns only 62 bits of >pseudo-randomness, because the underlying calls to lrand48() >"return non-negative long integers uniformly distributed >between 0 and 2^31." > >We have written a potential fix, but before we spend more >time testing and refining it, I wanted to check with you >guys. > >We switched to using the reentrant versions of [ls]rand48, >and maintain per-lcore state. We need ~2.06 calls to >lrand48_r(), per call to rte_rand(). > >Do you agree with the approach we've taken in this patch? > > >Thanks, >Robert > >--- > lib/librte_eal/common/include/rte_random.h | 33 >+++++++++++++++++++++++++-- > lib/librte_eal/linuxapp/eal/eal_thread.c | 7 ++++++ > 2 files changed, 37 insertions(+), 3 deletions(-) > >diff --git a/lib/librte_eal/common/include/rte_random.h >b/lib/librte_eal/common/include/rte_random.h >index 24ae836..b9248cd 100644 >--- a/lib/librte_eal/common/include/rte_random.h >+++ b/lib/librte_eal/common/include/rte_random.h >@@ -46,6 +46,17 @@ extern "C" { > > #include <stdint.h> > #include <stdlib.h> >+#include <rte_per_lcore.h> >+#include <rte_branch_prediction.h> >+ >+struct rte_rand_data { >+ struct drand48_data _dr48; >+ uint32_t _hi_bits; >+ uint8_t _bits_left; >+}; >+ >+RTE_DECLARE_PER_LCORE(struct rte_rand_data, _rand_data); >+ > > /** > * Seed the pseudo-random generator. >@@ -60,7 +71,7 @@ extern "C" { > static inline void > rte_srand(uint64_t seedval) > { >- srand48((long unsigned int)seedval); >+ srand48_r((long unsigned int)seedval, &RTE_PER_LCORE(_rand_data)._dr48); > } > > /** >@@ -76,10 +87,26 @@ rte_srand(uint64_t seedval) > static inline uint64_t > rte_rand(void) > { >+ struct rte_rand_data *rd = &RTE_PER_LCORE(_rand_data); > uint64_t val; >- val = lrand48(); >+ uint32_t hi_bits; >+ long int result; >+ >+ if (unlikely(rd->_bits_left < 2)) { >+ lrand48_r(&rd->_dr48, &result); >+ rd->_hi_bits |= (uint32_t)result << (1 - rd->_bits_left); >+ rd->_bits_left += 31; >+ } >+ >+ hi_bits = rd->_hi_bits; >+ lrand48_r(&rd->_dr48, &result); >+ val = (uint32_t)result | (hi_bits & 0x8000000); > val <<= 32; >- val += lrand48(); >+ hi_bits <<= 1; >+ lrand48_r(&rd->_dr48, &result); >+ val |= (uint32_t)result | (hi_bits & 0x8000000); >+ rd->_hi_bits = hi_bits << 1; >+ rd->_bits_left -= 2; > return val; > } > >diff --git a/lib/librte_eal/linuxapp/eal/eal_thread.c >b/lib/librte_eal/linuxapp/eal/eal_thread.c >index 5635c7d..08e7f72 100644 >--- a/lib/librte_eal/linuxapp/eal/eal_thread.c >+++ b/lib/librte_eal/linuxapp/eal/eal_thread.c >@@ -52,6 +52,8 @@ > #include <rte_eal.h> > #include <rte_per_lcore.h> > #include <rte_lcore.h> >+#include <rte_cycles.h> >+#include <rte_random.h> > > #include "eal_private.h" > #include "eal_thread.h" >@@ -59,6 +61,8 @@ > RTE_DEFINE_PER_LCORE(unsigned, _lcore_id) = LCORE_ID_ANY; > RTE_DEFINE_PER_LCORE(unsigned, _socket_id) = (unsigned)SOCKET_ID_ANY; > RTE_DEFINE_PER_LCORE(rte_cpuset_t, _cpuset); >+RTE_DEFINE_PER_LCORE(struct rte_rand_data, _rand_data); >+ > > /* > * Send a message to a slave lcore identified by slave_id to call a >@@ -147,6 +151,9 @@ eal_thread_loop(__attribute__((unused)) void *arg) > /* set the lcore ID in per-lcore memory area */ > RTE_PER_LCORE(_lcore_id) = lcore_id; > >+ /* seed per-lcore PRNG */ >+ rte_srand(rte_rdtsc()); >+ > /* set CPU affinity */ > if (eal_thread_set_affinity() < 0) > rte_panic("cannot set affinity\n"); >-- >1.7.1 > ^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [dpdk-dev] [RFC PATCH] eal: rte_rand yields only 62 random bits 2015-03-27 16:38 ` Sanford, Robert @ 2015-03-28 0:02 ` Stephen Hemminger 2015-03-28 0:03 ` Stephen Hemminger 1 sibling, 0 replies; 9+ messages in thread From: Stephen Hemminger @ 2015-03-28 0:02 UTC (permalink / raw) To: Sanford, Robert; +Cc: dev Please do this work upstream in glibc rather than in the corner case of DPDK. On Fri, Mar 27, 2015 at 9:38 AM, Sanford, Robert <rsanford@akamai.com> wrote: > Never mind ... I cancel the previous suggestion. After further reading on > RNGs, I believe we should abandon the use of lrand48() and implement our > own RNG based on the so-called KISS family of RNGs originally proposed by > the late George Marsaglia. In his excellent paper, "Good Practice in > (Pseudo) Random Number Generation for Bioinformatics Applications", David > Jones (UCL Bioinformatics Group) describes a few variants of KISS > generators. This paper, and Robert G. Brown's (Duke Univ.) comprehensive > "Dieharder" random number test suite work show that KISS RNGs are simple > and fast, yet high quality. > > Something like JLKISS64(), with state kept in TLS, would be ideal for DPDK > use. In limited experiments, I found JLKISS64() (not inlined, compiles to > ~40 instructions) to be ~4 times faster than rte_rand(). This is probably > because JLKISS64() achieves integer-instruction parallelism, while > rte_rand(), with its two calls to lrand48(), nrand48_r(), and > __drand48_iterate(), does not (and all those calls!). > > Here is the JLKISS64() function, as it appears in Jones's GoodPracticeRNG > paper: > > --- > > > > > > > > > > /* Public domain code for JLKISS64 > RNG - long period KISS RNG > producing 64-bit results */ > > unsigned long long x = > 123456789123ULL,y = 987654321987ULL; /* Seed > variables */ > unsigned int z1 = 43219876, c1 = 6543217, z2 = 21987643, c2 = 1732654; /* > Seed variables */ > > unsigned long long JLKISS64() > { > > unsigned long long t; > > x = 1490024343005336237ULL * x + > 123456789; > y ^= y << 21; y ^= y >> 17; y ^= y << 30; /* Do not set y=0! */ > t = 4294584393ULL * z1 + c1; c1 = t >> 32; z1 = t; > t = 4246477509ULL * z2 + c2; c2 = t >> 32; z2 = t; > > return x + y + z1 + ((unsigned > long long)z2 << 32); /* Return 64-bit > result */ > } > > > > > > > > > -- > Regards, > Robert > > > > >The implementation of rte_rand() returns only 62 bits of > >pseudo-randomness, because the underlying calls to lrand48() > >"return non-negative long integers uniformly distributed > >between 0 and 2^31." > > > >We have written a potential fix, but before we spend more > >time testing and refining it, I wanted to check with you > >guys. > > > >We switched to using the reentrant versions of [ls]rand48, > >and maintain per-lcore state. We need ~2.06 calls to > >lrand48_r(), per call to rte_rand(). > > > >Do you agree with the approach we've taken in this patch? > > > > > >Thanks, > >Robert > > > >--- > > lib/librte_eal/common/include/rte_random.h | 33 > >+++++++++++++++++++++++++-- > > lib/librte_eal/linuxapp/eal/eal_thread.c | 7 ++++++ > > 2 files changed, 37 insertions(+), 3 deletions(-) > > > >diff --git a/lib/librte_eal/common/include/rte_random.h > >b/lib/librte_eal/common/include/rte_random.h > >index 24ae836..b9248cd 100644 > >--- a/lib/librte_eal/common/include/rte_random.h > >+++ b/lib/librte_eal/common/include/rte_random.h > >@@ -46,6 +46,17 @@ extern "C" { > > > > #include <stdint.h> > > #include <stdlib.h> > >+#include <rte_per_lcore.h> > >+#include <rte_branch_prediction.h> > >+ > >+struct rte_rand_data { > >+ struct drand48_data _dr48; > >+ uint32_t _hi_bits; > >+ uint8_t _bits_left; > >+}; > >+ > >+RTE_DECLARE_PER_LCORE(struct rte_rand_data, _rand_data); > >+ > > > > /** > > * Seed the pseudo-random generator. > >@@ -60,7 +71,7 @@ extern "C" { > > static inline void > > rte_srand(uint64_t seedval) > > { > >- srand48((long unsigned int)seedval); > >+ srand48_r((long unsigned int)seedval, > &RTE_PER_LCORE(_rand_data)._dr48); > > } > > > > /** > >@@ -76,10 +87,26 @@ rte_srand(uint64_t seedval) > > static inline uint64_t > > rte_rand(void) > > { > >+ struct rte_rand_data *rd = &RTE_PER_LCORE(_rand_data); > > uint64_t val; > >- val = lrand48(); > >+ uint32_t hi_bits; > >+ long int result; > >+ > >+ if (unlikely(rd->_bits_left < 2)) { > >+ lrand48_r(&rd->_dr48, &result); > >+ rd->_hi_bits |= (uint32_t)result << (1 - rd->_bits_left); > >+ rd->_bits_left += 31; > >+ } > >+ > >+ hi_bits = rd->_hi_bits; > >+ lrand48_r(&rd->_dr48, &result); > >+ val = (uint32_t)result | (hi_bits & 0x8000000); > > val <<= 32; > >- val += lrand48(); > >+ hi_bits <<= 1; > >+ lrand48_r(&rd->_dr48, &result); > >+ val |= (uint32_t)result | (hi_bits & 0x8000000); > >+ rd->_hi_bits = hi_bits << 1; > >+ rd->_bits_left -= 2; > > return val; > > } > > > >diff --git a/lib/librte_eal/linuxapp/eal/eal_thread.c > >b/lib/librte_eal/linuxapp/eal/eal_thread.c > >index 5635c7d..08e7f72 100644 > >--- a/lib/librte_eal/linuxapp/eal/eal_thread.c > >+++ b/lib/librte_eal/linuxapp/eal/eal_thread.c > >@@ -52,6 +52,8 @@ > > #include <rte_eal.h> > > #include <rte_per_lcore.h> > > #include <rte_lcore.h> > >+#include <rte_cycles.h> > >+#include <rte_random.h> > > > > #include "eal_private.h" > > #include "eal_thread.h" > >@@ -59,6 +61,8 @@ > > RTE_DEFINE_PER_LCORE(unsigned, _lcore_id) = LCORE_ID_ANY; > > RTE_DEFINE_PER_LCORE(unsigned, _socket_id) = (unsigned)SOCKET_ID_ANY; > > RTE_DEFINE_PER_LCORE(rte_cpuset_t, _cpuset); > >+RTE_DEFINE_PER_LCORE(struct rte_rand_data, _rand_data); > >+ > > > > /* > > * Send a message to a slave lcore identified by slave_id to call a > >@@ -147,6 +151,9 @@ eal_thread_loop(__attribute__((unused)) void *arg) > > /* set the lcore ID in per-lcore memory area */ > > RTE_PER_LCORE(_lcore_id) = lcore_id; > > > >+ /* seed per-lcore PRNG */ > >+ rte_srand(rte_rdtsc()); > >+ > > /* set CPU affinity */ > > if (eal_thread_set_affinity() < 0) > > rte_panic("cannot set affinity\n"); > >-- > >1.7.1 > > > > ^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [dpdk-dev] [RFC PATCH] eal: rte_rand yields only 62 random bits 2015-03-27 16:38 ` Sanford, Robert 2015-03-28 0:02 ` Stephen Hemminger @ 2015-03-28 0:03 ` Stephen Hemminger 2015-03-28 0:38 ` Matthew Hall 1 sibling, 1 reply; 9+ messages in thread From: Stephen Hemminger @ 2015-03-28 0:03 UTC (permalink / raw) To: Sanford, Robert; +Cc: dev I would argue remove rte_rand from DPDK. On Fri, Mar 27, 2015 at 9:38 AM, Sanford, Robert <rsanford@akamai.com> wrote: > Never mind ... I cancel the previous suggestion. After further reading on > RNGs, I believe we should abandon the use of lrand48() and implement our > own RNG based on the so-called KISS family of RNGs originally proposed by > the late George Marsaglia. In his excellent paper, "Good Practice in > (Pseudo) Random Number Generation for Bioinformatics Applications", David > Jones (UCL Bioinformatics Group) describes a few variants of KISS > generators. This paper, and Robert G. Brown's (Duke Univ.) comprehensive > "Dieharder" random number test suite work show that KISS RNGs are simple > and fast, yet high quality. > > Something like JLKISS64(), with state kept in TLS, would be ideal for DPDK > use. In limited experiments, I found JLKISS64() (not inlined, compiles to > ~40 instructions) to be ~4 times faster than rte_rand(). This is probably > because JLKISS64() achieves integer-instruction parallelism, while > rte_rand(), with its two calls to lrand48(), nrand48_r(), and > __drand48_iterate(), does not (and all those calls!). > > Here is the JLKISS64() function, as it appears in Jones's GoodPracticeRNG > paper: > > --- > > > > > > > > > > /* Public domain code for JLKISS64 > RNG - long period KISS RNG > producing 64-bit results */ > > unsigned long long x = > 123456789123ULL,y = 987654321987ULL; /* Seed > variables */ > unsigned int z1 = 43219876, c1 = 6543217, z2 = 21987643, c2 = 1732654; /* > Seed variables */ > > unsigned long long JLKISS64() > { > > unsigned long long t; > > x = 1490024343005336237ULL * x + > 123456789; > y ^= y << 21; y ^= y >> 17; y ^= y << 30; /* Do not set y=0! */ > t = 4294584393ULL * z1 + c1; c1 = t >> 32; z1 = t; > t = 4246477509ULL * z2 + c2; c2 = t >> 32; z2 = t; > > return x + y + z1 + ((unsigned > long long)z2 << 32); /* Return 64-bit > result */ > } > > > > > > > > > -- > Regards, > Robert > > > > >The implementation of rte_rand() returns only 62 bits of > >pseudo-randomness, because the underlying calls to lrand48() > >"return non-negative long integers uniformly distributed > >between 0 and 2^31." > > > >We have written a potential fix, but before we spend more > >time testing and refining it, I wanted to check with you > >guys. > > > >We switched to using the reentrant versions of [ls]rand48, > >and maintain per-lcore state. We need ~2.06 calls to > >lrand48_r(), per call to rte_rand(). > > > >Do you agree with the approach we've taken in this patch? > > > > > >Thanks, > >Robert > > > >--- > > lib/librte_eal/common/include/rte_random.h | 33 > >+++++++++++++++++++++++++-- > > lib/librte_eal/linuxapp/eal/eal_thread.c | 7 ++++++ > > 2 files changed, 37 insertions(+), 3 deletions(-) > > > >diff --git a/lib/librte_eal/common/include/rte_random.h > >b/lib/librte_eal/common/include/rte_random.h > >index 24ae836..b9248cd 100644 > >--- a/lib/librte_eal/common/include/rte_random.h > >+++ b/lib/librte_eal/common/include/rte_random.h > >@@ -46,6 +46,17 @@ extern "C" { > > > > #include <stdint.h> > > #include <stdlib.h> > >+#include <rte_per_lcore.h> > >+#include <rte_branch_prediction.h> > >+ > >+struct rte_rand_data { > >+ struct drand48_data _dr48; > >+ uint32_t _hi_bits; > >+ uint8_t _bits_left; > >+}; > >+ > >+RTE_DECLARE_PER_LCORE(struct rte_rand_data, _rand_data); > >+ > > > > /** > > * Seed the pseudo-random generator. > >@@ -60,7 +71,7 @@ extern "C" { > > static inline void > > rte_srand(uint64_t seedval) > > { > >- srand48((long unsigned int)seedval); > >+ srand48_r((long unsigned int)seedval, > &RTE_PER_LCORE(_rand_data)._dr48); > > } > > > > /** > >@@ -76,10 +87,26 @@ rte_srand(uint64_t seedval) > > static inline uint64_t > > rte_rand(void) > > { > >+ struct rte_rand_data *rd = &RTE_PER_LCORE(_rand_data); > > uint64_t val; > >- val = lrand48(); > >+ uint32_t hi_bits; > >+ long int result; > >+ > >+ if (unlikely(rd->_bits_left < 2)) { > >+ lrand48_r(&rd->_dr48, &result); > >+ rd->_hi_bits |= (uint32_t)result << (1 - rd->_bits_left); > >+ rd->_bits_left += 31; > >+ } > >+ > >+ hi_bits = rd->_hi_bits; > >+ lrand48_r(&rd->_dr48, &result); > >+ val = (uint32_t)result | (hi_bits & 0x8000000); > > val <<= 32; > >- val += lrand48(); > >+ hi_bits <<= 1; > >+ lrand48_r(&rd->_dr48, &result); > >+ val |= (uint32_t)result | (hi_bits & 0x8000000); > >+ rd->_hi_bits = hi_bits << 1; > >+ rd->_bits_left -= 2; > > return val; > > } > > > >diff --git a/lib/librte_eal/linuxapp/eal/eal_thread.c > >b/lib/librte_eal/linuxapp/eal/eal_thread.c > >index 5635c7d..08e7f72 100644 > >--- a/lib/librte_eal/linuxapp/eal/eal_thread.c > >+++ b/lib/librte_eal/linuxapp/eal/eal_thread.c > >@@ -52,6 +52,8 @@ > > #include <rte_eal.h> > > #include <rte_per_lcore.h> > > #include <rte_lcore.h> > >+#include <rte_cycles.h> > >+#include <rte_random.h> > > > > #include "eal_private.h" > > #include "eal_thread.h" > >@@ -59,6 +61,8 @@ > > RTE_DEFINE_PER_LCORE(unsigned, _lcore_id) = LCORE_ID_ANY; > > RTE_DEFINE_PER_LCORE(unsigned, _socket_id) = (unsigned)SOCKET_ID_ANY; > > RTE_DEFINE_PER_LCORE(rte_cpuset_t, _cpuset); > >+RTE_DEFINE_PER_LCORE(struct rte_rand_data, _rand_data); > >+ > > > > /* > > * Send a message to a slave lcore identified by slave_id to call a > >@@ -147,6 +151,9 @@ eal_thread_loop(__attribute__((unused)) void *arg) > > /* set the lcore ID in per-lcore memory area */ > > RTE_PER_LCORE(_lcore_id) = lcore_id; > > > >+ /* seed per-lcore PRNG */ > >+ rte_srand(rte_rdtsc()); > >+ > > /* set CPU affinity */ > > if (eal_thread_set_affinity() < 0) > > rte_panic("cannot set affinity\n"); > >-- > >1.7.1 > > > > ^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [dpdk-dev] [RFC PATCH] eal: rte_rand yields only 62 random bits 2015-03-28 0:03 ` Stephen Hemminger @ 2015-03-28 0:38 ` Matthew Hall 2015-03-30 5:28 ` Stephen Hemminger 0 siblings, 1 reply; 9+ messages in thread From: Matthew Hall @ 2015-03-28 0:38 UTC (permalink / raw) To: Stephen Hemminger; +Cc: dev On Fri, Mar 27, 2015 at 05:03:02PM -0700, Stephen Hemminger wrote: > I would argue remove rte_rand from DPDK. +1 To paraphrase Donald Knuth, "Random numbers should not be generated [using a function coded] at random." It'd be better to fix libc, or considering that has a slow dev cycle and platform compatibility limits, use some simple, semi-random, high-performance BSD licensed routine from a known-good library. Matthew. ^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [dpdk-dev] [RFC PATCH] eal: rte_rand yields only 62 random bits 2015-03-28 0:38 ` Matthew Hall @ 2015-03-30 5:28 ` Stephen Hemminger 2015-03-30 22:19 ` Robert Sanford 0 siblings, 1 reply; 9+ messages in thread From: Stephen Hemminger @ 2015-03-30 5:28 UTC (permalink / raw) To: Matthew Hall; +Cc: dev if some one needs PRNG, th GNU scientific library has lots of them https://www.gnu.org/software/gsl/manual/html_node/Random-number-generator-algorithms.html On Fri, Mar 27, 2015 at 5:38 PM, Matthew Hall <mhall@mhcomputing.net> wrote: > On Fri, Mar 27, 2015 at 05:03:02PM -0700, Stephen Hemminger wrote: > > I would argue remove rte_rand from DPDK. > > +1 > > To paraphrase Donald Knuth, "Random numbers should not be generated [using > a > function coded] at random." > > It'd be better to fix libc, or considering that has a slow dev cycle and > platform compatibility limits, use some simple, semi-random, > high-performance > BSD licensed routine from a known-good library. > > Matthew. > ^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [dpdk-dev] [RFC PATCH] eal: rte_rand yields only 62 random bits 2015-03-30 5:28 ` Stephen Hemminger @ 2015-03-30 22:19 ` Robert Sanford 2015-03-31 1:51 ` Neil Horman 0 siblings, 1 reply; 9+ messages in thread From: Robert Sanford @ 2015-03-30 22:19 UTC (permalink / raw) To: Stephen Hemminger; +Cc: dev Yes, applications have many choices for PRNGs. But, we still need one internally for the following libs: PMDs (e1000, fm10k, i40e, ixgbe, virtio, xenvirt), sched, and timer. On Fri, Mar 27, 2015 at 8:03 PM, Stephen Hemminger < stephen@networkplumber.org> wrote: > I would argue remove rte_rand from DPDK. On Mon, Mar 30, 2015 at 1:28 AM, Stephen Hemminger < stephen@networkplumber.org> wrote: > if some one needs PRNG, th GNU scientific library has lots of them > > https://www.gnu.org/software/gsl/manual/html_node/Random-number-generator-algorithms.html > > On Fri, Mar 27, 2015 at 5:38 PM, Matthew Hall <mhall@mhcomputing.net> > wrote: > > > On Fri, Mar 27, 2015 at 05:03:02PM -0700, Stephen Hemminger wrote: > > > I would argue remove rte_rand from DPDK. > > > > +1 > > > > To paraphrase Donald Knuth, "Random numbers should not be generated > [using > > a > > function coded] at random." > > > > It'd be better to fix libc, or considering that has a slow dev cycle and > > platform compatibility limits, use some simple, semi-random, > > high-performance > > BSD licensed routine from a known-good library. > > > > Matthew. > > > ^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [dpdk-dev] [RFC PATCH] eal: rte_rand yields only 62 random bits 2015-03-30 22:19 ` Robert Sanford @ 2015-03-31 1:51 ` Neil Horman 2015-04-01 2:17 ` Stephen Hemminger 0 siblings, 1 reply; 9+ messages in thread From: Neil Horman @ 2015-03-31 1:51 UTC (permalink / raw) To: Robert Sanford; +Cc: dev On Mon, Mar 30, 2015 at 06:19:28PM -0400, Robert Sanford wrote: > Yes, applications have many choices for PRNGs. But, we still need one > internally for the following libs: PMDs (e1000, fm10k, i40e, ixgbe, virtio, > xenvirt), sched, and timer. > They can be updated to use the apropriate rng from an external library. Neil > > On Fri, Mar 27, 2015 at 8:03 PM, Stephen Hemminger < > stephen@networkplumber.org> wrote: > > I would argue remove rte_rand from DPDK. > > > > On Mon, Mar 30, 2015 at 1:28 AM, Stephen Hemminger < > stephen@networkplumber.org> wrote: > > > if some one needs PRNG, th GNU scientific library has lots of them > > > > https://www.gnu.org/software/gsl/manual/html_node/Random-number-generator-algorithms.html > > > > On Fri, Mar 27, 2015 at 5:38 PM, Matthew Hall <mhall@mhcomputing.net> > > wrote: > > > > > On Fri, Mar 27, 2015 at 05:03:02PM -0700, Stephen Hemminger wrote: > > > > I would argue remove rte_rand from DPDK. > > > > > > +1 > > > > > > To paraphrase Donald Knuth, "Random numbers should not be generated > > [using > > > a > > > function coded] at random." > > > > > > It'd be better to fix libc, or considering that has a slow dev cycle and > > > platform compatibility limits, use some simple, semi-random, > > > high-performance > > > BSD licensed routine from a known-good library. > > > > > > Matthew. > > > > > > ^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [dpdk-dev] [RFC PATCH] eal: rte_rand yields only 62 random bits 2015-03-31 1:51 ` Neil Horman @ 2015-04-01 2:17 ` Stephen Hemminger 0 siblings, 0 replies; 9+ messages in thread From: Stephen Hemminger @ 2015-04-01 2:17 UTC (permalink / raw) To: Neil Horman; +Cc: dev Plus the driver and sched uses really only need of few bits of crap random number. Probably simple BSD random (32 bits) is more than enough On Mon, Mar 30, 2015 at 6:51 PM, Neil Horman <nhorman@tuxdriver.com> wrote: > On Mon, Mar 30, 2015 at 06:19:28PM -0400, Robert Sanford wrote: > > Yes, applications have many choices for PRNGs. But, we still need one > > internally for the following libs: PMDs (e1000, fm10k, i40e, ixgbe, > virtio, > > xenvirt), sched, and timer. > > > They can be updated to use the apropriate rng from an external library. > Neil > > > > > On Fri, Mar 27, 2015 at 8:03 PM, Stephen Hemminger < > > stephen@networkplumber.org> wrote: > > > I would argue remove rte_rand from DPDK. > > > > > > > > On Mon, Mar 30, 2015 at 1:28 AM, Stephen Hemminger < > > stephen@networkplumber.org> wrote: > > > > > if some one needs PRNG, th GNU scientific library has lots of them > > > > > > > https://www.gnu.org/software/gsl/manual/html_node/Random-number-generator-algorithms.html > > > > > > On Fri, Mar 27, 2015 at 5:38 PM, Matthew Hall <mhall@mhcomputing.net> > > > wrote: > > > > > > > On Fri, Mar 27, 2015 at 05:03:02PM -0700, Stephen Hemminger wrote: > > > > > I would argue remove rte_rand from DPDK. > > > > > > > > +1 > > > > > > > > To paraphrase Donald Knuth, "Random numbers should not be generated > > > [using > > > > a > > > > function coded] at random." > > > > > > > > It'd be better to fix libc, or considering that has a slow dev cycle > and > > > > platform compatibility limits, use some simple, semi-random, > > > > high-performance > > > > BSD licensed routine from a known-good library. > > > > > > > > Matthew. > > > > > > > > > > ^ permalink raw reply [flat|nested] 9+ messages in thread
end of thread, other threads:[~2015-04-01 2:17 UTC | newest] Thread overview: 9+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2015-03-17 16:18 [dpdk-dev] [RFC PATCH] eal: rte_rand yields only 62 random bits Robert Sanford 2015-03-27 16:38 ` Sanford, Robert 2015-03-28 0:02 ` Stephen Hemminger 2015-03-28 0:03 ` Stephen Hemminger 2015-03-28 0:38 ` Matthew Hall 2015-03-30 5:28 ` Stephen Hemminger 2015-03-30 22:19 ` Robert Sanford 2015-03-31 1:51 ` Neil Horman 2015-04-01 2:17 ` Stephen Hemminger
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