From: Bruce Richardson <bruce.richardson@intel.com>
To: Marc Sune <marc.sune@bisdn.de>
Cc: dev@dpdk.org
Subject: Re: [dpdk-dev] [PATCH 0/4] DPDK memcpy optimization
Date: Wed, 21 Jan 2015 13:26:20 +0000 [thread overview]
Message-ID: <20150121132620.GC10756@bricha3-MOBL3> (raw)
In-Reply-To: <54BFA7D5.7020106@bisdn.de>
On Wed, Jan 21, 2015 at 02:21:25PM +0100, Marc Sune wrote:
>
> On 21/01/15 14:02, Bruce Richardson wrote:
> >On Wed, Jan 21, 2015 at 01:36:41PM +0100, Marc Sune wrote:
> >>On 21/01/15 04:44, Wang, Zhihong wrote:
> >>>>-----Original Message-----
> >>>>From: Richardson, Bruce
> >>>>Sent: Wednesday, January 21, 2015 12:15 AM
> >>>>To: Neil Horman
> >>>>Cc: Wang, Zhihong; dev@dpdk.org
> >>>>Subject: Re: [dpdk-dev] [PATCH 0/4] DPDK memcpy optimization
> >>>>
> >>>>On Tue, Jan 20, 2015 at 10:11:18AM -0500, Neil Horman wrote:
> >>>>>On Tue, Jan 20, 2015 at 03:01:44AM +0000, Wang, Zhihong wrote:
> >>>>>>>-----Original Message-----
> >>>>>>>From: Neil Horman [mailto:nhorman@tuxdriver.com]
> >>>>>>>Sent: Monday, January 19, 2015 9:02 PM
> >>>>>>>To: Wang, Zhihong
> >>>>>>>Cc: dev@dpdk.org
> >>>>>>>Subject: Re: [dpdk-dev] [PATCH 0/4] DPDK memcpy optimization
> >>>>>>>
> >>>>>>>On Mon, Jan 19, 2015 at 09:53:30AM +0800, zhihong.wang@intel.com
> >>>>wrote:
> >>>>>>>>This patch set optimizes memcpy for DPDK for both SSE and AVX
> >>>>platforms.
> >>>>>>>>It also extends memcpy test coverage with unaligned cases and
> >>>>>>>>more test
> >>>>>>>points.
> >>>>>>>>Optimization techniques are summarized below:
> >>>>>>>>
> >>>>>>>>1. Utilize full cache bandwidth
> >>>>>>>>
> >>>>>>>>2. Enforce aligned stores
> >>>>>>>>
> >>>>>>>>3. Apply load address alignment based on architecture features
> >>>>>>>>
> >>>>>>>>4. Make load/store address available as early as possible
> >>>>>>>>
> >>>>>>>>5. General optimization techniques like inlining, branch
> >>>>>>>>reducing, prefetch pattern access
> >>>>>>>>
> >>>>>>>>Zhihong Wang (4):
> >>>>>>>> Disabled VTA for memcpy test in app/test/Makefile
> >>>>>>>> Removed unnecessary test cases in test_memcpy.c
> >>>>>>>> Extended test coverage in test_memcpy_perf.c
> >>>>>>>> Optimized memcpy in arch/x86/rte_memcpy.h for both SSE and AVX
> >>>>>>>> platforms
> >>>>>>>>
> >>>>>>>> app/test/Makefile | 6 +
> >>>>>>>> app/test/test_memcpy.c | 52 +-
> >>>>>>>> app/test/test_memcpy_perf.c | 238 +++++---
> >>>>>>>> .../common/include/arch/x86/rte_memcpy.h | 664
> >>>>>>>+++++++++++++++------
> >>>>>>>> 4 files changed, 656 insertions(+), 304 deletions(-)
> >>>>>>>>
> >>>>>>>>--
> >>>>>>>>1.9.3
> >>>>>>>>
> >>>>>>>>
> >>>>>>>Are you able to compile this with gcc 4.9.2? The compilation of
> >>>>>>>test_memcpy_perf is taking forever for me. It appears hung.
> >>>>>>>Neil
> >>>>>>Neil,
> >>>>>>
> >>>>>>Thanks for reporting this!
> >>>>>>It should compile but will take quite some time if the CPU doesn't support
> >>>>AVX2, the reason is that:
> >>>>>>1. The SSE & AVX memcpy implementation is more complicated than
> >>>>AVX2
> >>>>>>version thus the compiler takes more time to compile and optimize 2.
> >>>>>>The new test_memcpy_perf.c contains 126 constants memcpy calls for
> >>>>>>better test case coverage, that's quite a lot
> >>>>>>
> >>>>>>I've just tested this patch on an Ivy Bridge machine with GCC 4.9.2:
> >>>>>>1. The whole compile process takes 9'41" with the original
> >>>>>>test_memcpy_perf.c (63 + 63 = 126 constant memcpy calls) 2. It takes
> >>>>>>only 2'41" after I reduce the constant memcpy call number to 12 + 12
> >>>>>>= 24
> >>>>>>
> >>>>>>I'll reduce memcpy call in the next version of patch.
> >>>>>>
> >>>>>ok, thank you. I'm all for optimzation, but I think a compile that
> >>>>>takes almost
> >>>>>10 minutes for a single file is going to generate some raised eyebrows
> >>>>>when end users start tinkering with it
> >>>>>
> >>>>>Neil
> >>>>>
> >>>>>>Zhihong (John)
> >>>>>>
> >>>>Even two minutes is a very long time to compile, IMHO. The whole of DPDK
> >>>>doesn't take that long to compile right now, and that's with a couple of huge
> >>>>header files with routing tables in it. Any chance you could cut compile time
> >>>>down to a few seconds while still having reasonable tests?
> >>>>Also, when there is AVX2 present on the system, what is the compile time
> >>>>like for that code?
> >>>>
> >>>> /Bruce
> >>>Neil, Bruce,
> >>>
> >>>Some data first.
> >>>
> >>>Sandy Bridge without AVX2:
> >>>1. original w/ 10 constant memcpy: 2'25"
> >>>2. patch w/ 12 constant memcpy: 2'41"
> >>>3. patch w/ 63 constant memcpy: 9'41"
> >>>
> >>>Haswell with AVX2:
> >>>1. original w/ 10 constant memcpy: 1'57"
> >>>2. patch w/ 12 constant memcpy: 1'56"
> >>>3. patch w/ 63 constant memcpy: 3'16"
> >>>
> >>>Also, to address Bruce's question, we have to reduce test case to cut down compile time. Because we use:
> >>>1. intrinsics instead of assembly for better flexibility and can utilize more compiler optimization
> >>>2. complex function body for better performance
> >>>3. inlining
> >>>This increases compile time.
> >>>But I think it'd be okay to do that as long as we can select a fair set of test points.
> >>>
> >>>It'd be great if you could give some suggestion, say, 12 points.
> >>>
> >>>Zhihong (John)
> >>>
> >>>
> >>While I agree in the general case these long compilation times is painful
> >>for the users, having a factor of 2-8x in memcpy operations is quite an
> >>improvement, specially in DPDK applications which need to deal
> >>(unfortunately) heavily on them -- e.g. IP fragmentation and reassembly.
> >>
> >>Why not having a fast compilation by default, and a tunable config flag to
> >>enable a highly optimized version of rte_memcpy (e.g. RTE_EAL_OPT_MEMCPY)?
> >>
> >>Marc
> >>
> >Out of interest, are these 2-8x improvements something you have benchmarked
> >in these app scenarios? [i.e. not just in micro-benchmarks].
>
> How much that micro-speedup will end up affecting the performance of the
> entire application is something I cannot say, so I agree that we should
> probably have some additional benchmarks before deciding that pays off
> maintaining 2 versions of rte_memcpy.
>
> There are however a bunch of possible DPDK applications that could
> potentially benefit; IP fragmentation, tunneling and specialized DPI
> applications, among others, since they involve a reasonable amount of
> memcpys per pkt. My point was, *if* it proves that is enough beneficial, why
> not having it optionally?
>
> Marc
I agree, if it provides the speedups then we need to have it in - and quite possibly
on by default, even.
/Bruce
next prev parent reply other threads:[~2015-01-21 13:27 UTC|newest]
Thread overview: 48+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-01-19 1:53 zhihong.wang
2015-01-19 1:53 ` [dpdk-dev] [PATCH 1/4] app/test: Disabled VTA for memcpy test in app/test/Makefile zhihong.wang
2015-01-19 1:53 ` [dpdk-dev] [PATCH 2/4] app/test: Removed unnecessary test cases in test_memcpy.c zhihong.wang
2015-01-19 1:53 ` [dpdk-dev] [PATCH 3/4] app/test: Extended test coverage in test_memcpy_perf.c zhihong.wang
2015-01-19 1:53 ` [dpdk-dev] [PATCH 4/4] lib/librte_eal: Optimized memcpy in arch/x86/rte_memcpy.h for both SSE and AVX platforms zhihong.wang
2015-01-20 17:15 ` Stephen Hemminger
2015-01-20 19:16 ` Neil Horman
2015-01-21 3:18 ` Wang, Zhihong
2015-01-25 20:02 ` Jim Thompson
2015-01-26 14:43 ` Wodkowski, PawelX
2015-01-27 5:12 ` Wang, Zhihong
2015-01-19 13:02 ` [dpdk-dev] [PATCH 0/4] DPDK memcpy optimization Neil Horman
2015-01-20 3:01 ` Wang, Zhihong
2015-01-20 15:11 ` Neil Horman
2015-01-20 16:14 ` Bruce Richardson
2015-01-21 3:44 ` Wang, Zhihong
2015-01-21 11:40 ` Bruce Richardson
2015-01-21 12:02 ` Ananyev, Konstantin
2015-01-21 12:38 ` Neil Horman
2015-01-23 3:26 ` Wang, Zhihong
2015-01-21 12:36 ` Marc Sune
2015-01-21 13:02 ` Bruce Richardson
2015-01-21 13:21 ` Marc Sune
2015-01-21 13:26 ` Bruce Richardson [this message]
2015-01-21 19:49 ` Stephen Hemminger
2015-01-21 20:54 ` Neil Horman
2015-01-21 21:25 ` Jim Thompson
2015-01-22 0:53 ` Stephen Hemminger
2015-01-22 9:06 ` Luke Gorrie
2015-01-22 13:29 ` Jay Rolette
2015-01-22 18:27 ` Luke Gorrie
2015-01-22 19:36 ` Jay Rolette
2015-01-22 18:21 ` EDMISON, Kelvin (Kelvin)
2015-01-27 8:22 ` Wang, Zhihong
2015-01-28 21:48 ` EDMISON, Kelvin (Kelvin)
2015-01-29 1:53 ` Wang, Zhihong
2015-01-23 6:52 ` Wang, Zhihong
2015-01-26 18:29 ` Ananyev, Konstantin
2015-01-27 1:42 ` Wang, Zhihong
2015-01-27 11:30 ` Ananyev, Konstantin
2015-01-27 12:19 ` Ananyev, Konstantin
2015-01-28 2:06 ` Wang, Zhihong
2015-01-25 14:50 ` Luke Gorrie
2015-01-26 1:30 ` Wang, Zhihong
2015-01-26 8:03 ` Luke Gorrie
2015-01-27 7:19 ` Wang, Zhihong
2015-01-27 13:57 ` [dpdk-dev] [snabb-devel] " Luke Gorrie
2015-01-29 3:42 ` [dpdk-dev] " Fu, JingguoX
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