From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mga11.intel.com (mga11.intel.com [192.55.52.93]) by dpdk.org (Postfix) with ESMTP id AF8DE2A1A for ; Fri, 19 Dec 2014 02:29:18 +0100 (CET) Received: from fmsmga002.fm.intel.com ([10.253.24.26]) by fmsmga102.fm.intel.com with ESMTP; 18 Dec 2014 17:29:17 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.07,604,1413270000"; d="scan'208";a="650221399" Received: from pgsmsx104.gar.corp.intel.com ([10.221.44.91]) by fmsmga002.fm.intel.com with ESMTP; 18 Dec 2014 17:29:16 -0800 Received: from shsmsx104.ccr.corp.intel.com (10.239.4.70) by PGSMSX104.gar.corp.intel.com (10.221.44.91) with Microsoft SMTP Server (TLS) id 14.3.195.1; Fri, 19 Dec 2014 09:29:11 +0800 Received: from shsmsx102.ccr.corp.intel.com ([169.254.2.216]) by SHSMSX104.ccr.corp.intel.com ([169.254.5.182]) with mapi id 14.03.0195.001; Fri, 19 Dec 2014 09:28:49 +0800 From: "Liang, Cunming" To: "Walukiewicz, Miroslaw" , "dev@dpdk.org" Thread-Topic: [dpdk-dev] [RFC PATCH 0/7] support multi-phtread per lcore Thread-Index: AQHQFObgfmq64AgbV0e+OTw3KgLpHZyJoZWAgAGfW9CABL60AIAAkFJwgAQ6C4CAAV5A0A== Date: Fri, 19 Dec 2014 01:28:47 +0000 Message-ID: References: <1418263490-21088-1-git-send-email-cunming.liang@intel.com> <7C4248CAE043B144B1CD242D275626532FE15298@IRSMSX104.ger.corp.intel.com> <7C4248CAE043B144B1CD242D275626532FE232BA@IRSMSX104.ger.corp.intel.com> <7C4248CAE043B144B1CD242D275626532FE27C3B@IRSMSX104.ger.corp.intel.com> In-Reply-To: <7C4248CAE043B144B1CD242D275626532FE27C3B@IRSMSX104.ger.corp.intel.com> Accept-Language: zh-CN, en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [10.239.127.40] Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Subject: Re: [dpdk-dev] [RFC PATCH 0/7] support multi-phtread per lcore X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: patches and discussions about DPDK List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 19 Dec 2014 01:29:19 -0000 > -----Original Message----- > From: Walukiewicz, Miroslaw > Sent: Thursday, December 18, 2014 8:20 PM > To: Liang, Cunming; dev@dpdk.org > Subject: RE: [dpdk-dev] [RFC PATCH 0/7] support multi-phtread per lcore >=20 > I have another question regarding your patch. >=20 > Could we extend values returned by rte_lcore_id() to set them per thread= (really > the DPDK lcore is a pthread but started on specific core) instead of crea= ting linear > thread id. [Liang, Cunming] As you said, __lcore_id is already per thread.=20 Per the semantic meaning, it stands for logic cpu id.=20 When multi-thread running on the same lcore, they should get the same value= return by rte_lcore_id(). The same effective like 'schedu_getcpu()', but less using cost. >=20 > The patch would be much simpler and will work same way. The only change > would be extending rte_lcore_id when rte_pthread_create() is called. [Liang, Cunming] I ever think about it which using rte_lcore_id() to get un= ique id per pthread rather than have a new API. But the name lcore actually no longer identify for cpu id. It may impact al= l existing user application who use the exact meaning of it. How do you think ? >=20 > The value __lcore_id has really an attribute __thread that means it is va= lid not > only per CPU core but also per thread. >=20 > The mempools, timers, statistics would work without any modifications in = that > environment. >=20 > I do not see any reason why old legacy DPDK applications would not work = in that > model. >=20 > Mirek >=20 > > -----Original Message----- > > From: Liang, Cunming > > Sent: Monday, December 15, 2014 12:53 PM > > To: Walukiewicz, Miroslaw; dev@dpdk.org > > Subject: RE: [dpdk-dev] [RFC PATCH 0/7] support multi-phtread per lcore > > > > Hi Mirek, > > > > That sounds great. > > Looking forward to it. > > > > -Cunming > > > > > -----Original Message----- > > > From: Walukiewicz, Miroslaw > > > Sent: Monday, December 15, 2014 7:11 PM > > > To: Liang, Cunming; dev@dpdk.org > > > Subject: RE: [dpdk-dev] [RFC PATCH 0/7] support multi-phtread per lco= re > > > > > > Hi Cunming, > > > > > > The timers could be used by any application/library started as a stan= dard > > > pthread. > > > Each pthread needs to have assigned some identifier same way as you a= re > > doing > > > it for mempools (the rte_linear_thread_id and rte_lcore_id are good > > examples) > > > > > > I made series of patches extending the rte timers API to use with suc= h kind > > of > > > identifier keeping existing API working also. > > > > > > I will send it soon. > > > > > > Mirek > > > > > > > > > > -----Original Message----- > > > > From: Liang, Cunming > > > > Sent: Friday, December 12, 2014 6:45 AM > > > > To: Walukiewicz, Miroslaw; dev@dpdk.org > > > > Subject: RE: [dpdk-dev] [RFC PATCH 0/7] support multi-phtread per l= core > > > > > > > > Thanks Mirek. That's a good point which wasn't mentioned in cover > > letter. > > > > For 'rte_timer', I only expect it be used within the 'legacy per-lc= ore' > > pthread. > > > > I'm appreciate if you can give me some cases which can't use it to = fit. > > > > In case have to use 'rte_timer' in multi-pthread, there are some > > > > prerequisites and limitations. > > > > 1. Make sure thread local variable 'lcore_id' is set correctly (e.g= . do > > pthread > > > > init by rte_pthread_prepare) > > > > 2. As 'rte_timer' is not preemptable, when using > > rte_timer_manager/reset in > > > > multi-pthread, make sure they're not on the same core. > > > > > > > > -Cunming > > > > > > > > > -----Original Message----- > > > > > From: Walukiewicz, Miroslaw > > > > > Sent: Thursday, December 11, 2014 5:57 PM > > > > > To: Liang, Cunming; dev@dpdk.org > > > > > Subject: RE: [dpdk-dev] [RFC PATCH 0/7] support multi-phtread per > > lcore > > > > > > > > > > Thank you Cunming for explanation. > > > > > > > > > > What about DPDK timers? They also depend on rte_lcore_id() to avo= id > > > > spinlocks. > > > > > > > > > > Mirek > > > > > > > > > > > -----Original Message----- > > > > > > From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Cunming > > Liang > > > > > > Sent: Thursday, December 11, 2014 3:05 AM > > > > > > To: dev@dpdk.org > > > > > > Subject: [dpdk-dev] [RFC PATCH 0/7] support multi-phtread per l= core > > > > > > > > > > > > > > > > > > Scope & Usage Scenario > > > > > > =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D > > > > > > > > > > > > DPDK usually pin pthread per core to avoid task switch overhead= . It > > gains > > > > > > performance a lot, but it's not efficient in all cases. In some= cases, it > > may > > > > > > too expensive to use the whole core for a lightweight workload.= It's a > > > > > > reasonable demand to have multiple threads per core and each > > threads > > > > > > share CPU > > > > > > in an assigned weight. > > > > > > > > > > > > In fact, nothing avoid user to create normal pthread and using = cgroup > > to > > > > > > control the CPU share. One of the purpose for the patchset is t= o clean > > the > > > > > > gaps of using more DPDK libraries in the normal pthread. In add= ition, it > > > > > > demonstrates performance gain by proactive 'yield' when doing i= dle > > loop > > > > > > in packet IO. It also provides several 'rte_pthread_*' APIs to = easy life. > > > > > > > > > > > > > > > > > > Changes to DPDK libraries > > > > > > =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D > > > > > > > > > > > > Some of DPDK libraries must run in DPDK environment. > > > > > > > > > > > > # rte_mempool > > > > > > > > > > > > In rte_mempool doc, it mentions a thread not created by EAL mus= t > > not > > > > use > > > > > > mempools. The root cause is it uses a per-lcore cache inside > > mempool. > > > > > > And 'rte_lcore_id()' will not return a correct value. > > > > > > > > > > > > The patchset changes this a little. The index of mempool cache = won't > > be a > > > > > > lcore_id. Instead of it, using a linear number generated by the > > allocator. > > > > > > For those legacy EAL per-lcore thread, it apply for an unique l= inear id > > > > > > during creation. For those normal pthread expecting to use > > > > rte_mempool, it > > > > > > requires to apply for a linear id explicitly. Now the mempool c= ache > > looks > > > > like > > > > > > a per-thread base. The linear ID actually identify for the line= ar thread > > id. > > > > > > > > > > > > However, there's another problem. The rte_mempool is not > > > > preemptable. > > > > > > The > > > > > > problem comes from rte_ring, so talk together in next section. > > > > > > > > > > > > # rte_ring > > > > > > > > > > > > rte_ring supports multi-producer enqueue and multi-consumer > > > > dequeue. > > > > > > But it's > > > > > > not preemptable. There's conversation talking about this before= . > > > > > > http://dpdk.org/ml/archives/dev/2013-November/000714.html > > > > > > > > > > > > Let's say there's two pthreads running on the same core doing > > enqueue > > > > on > > > > > > the > > > > > > same rte_ring. If the 1st pthread is preempted by the 2nd pthre= ad > > while > > > > it > > > > > > has > > > > > > already modified the prod.head, the 2nd pthread will spin until= the 1st > > > > one > > > > > > scheduled agian. It causes time wasting. In addition, if the 2n= d > > pthread > > > > has > > > > > > absolutely higer priority, it's more terrible. > > > > > > > > > > > > But it doesn't means we can't use. Just need to narrow down the > > > > situation > > > > > > when > > > > > > it's used by multi-pthread on the same core. > > > > > > - It CAN be used for any single-producer or single-consumer sit= uation. > > > > > > - It MAY be used by multi-producer/consumer pthread whose > > scheduling > > > > > > policy > > > > > > are all SCHED_OTHER(cfs). User SHOULD aware of the performance > > > > penalty > > > > > > befor > > > > > > using it. > > > > > > - It MUST not be used by multi-producer/consumer pthread, while > > some > > > > of > > > > > > their > > > > > > scheduling policies is SCHED_FIFO or SCHED_RR. > > > > > > > > > > > > > > > > > > Performance > > > > > > =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D > > > > > > > > > > > > It loses performance by introducing task switching. On packet I= O > > > > perspective, > > > > > > we can gain some back by improving IO effective rate. When the > > pthread > > > > do > > > > > > idle > > > > > > loop on an empty rx queue, it should proactively yield. We can = also > > slow > > > > > > down > > > > > > rx for a bit while to take more advantage of the bulk receiving= in the > > next > > > > > > loop. In practice, increase the rx ring size also helps to impr= ove the > > > > overrall > > > > > > throughput. > > > > > > > > > > > > > > > > > > Cgroup Control > > > > > > =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D > > > > > > > > > > > > Here's a simple example, there's four pthread doing packet IO o= n the > > > > same > > > > > > core. > > > > > > We expect the CPU share rate is 1:1:2:4. > > > > > > > mkdir /sys/fs/cgroup/cpu/dpdk > > > > > > > mkdir /sys/fs/cgroup/cpu/dpdk/thread0 > > > > > > > mkdir /sys/fs/cgroup/cpu/dpdk/thread1 > > > > > > > mkdir /sys/fs/cgroup/cpu/dpdk/thread2 > > > > > > > mkdir /sys/fs/cgroup/cpu/dpdk/thread3 > > > > > > > cd /sys/fs/cgroup/cpu/dpdk > > > > > > > echo 256 > thread0/cpu.shares > > > > > > > echo 256 > thread1/cpu.shares > > > > > > > echo 512 > thread2/cpu.shares > > > > > > > echo 1024 > thread3/cpu.shares > > > > > > > > > > > > > > > > > > -END- > > > > > > > > > > > > Any comments are welcome. > > > > > > > > > > > > Thanks > > > > > > > > > > > > *** BLURB HERE *** > > > > > > > > > > > > Cunming Liang (7): > > > > > > eal: add linear thread id as pthread-local variable > > > > > > mempool: use linear-tid as mempool cache index > > > > > > ring: use linear-tid as ring debug stats index > > > > > > eal: add simple API for multi-pthread > > > > > > testpmd: support multi-pthread mode > > > > > > sample: add new sample for multi-pthread > > > > > > eal: macro for cpuset w/ or w/o CPU_ALLOC > > > > > > > > > > > > app/test-pmd/cmdline.c | 41 +++++ > > > > > > app/test-pmd/testpmd.c | 84 ++++++++- > > > > > > app/test-pmd/testpmd.h | 1 + > > > > > > config/common_linuxapp | 1 + > > > > > > examples/multi-pthread/Makefile | 57 ++++++ > > > > > > examples/multi-pthread/main.c | 232 > > > > > ++++++++++++++++++++++++ > > > > > > examples/multi-pthread/main.h | 46 +++++ > > > > > > lib/librte_eal/common/include/rte_eal.h | 15 ++ > > > > > > lib/librte_eal/common/include/rte_lcore.h | 12 ++ > > > > > > lib/librte_eal/linuxapp/eal/eal_thread.c | 282 > > > > > > +++++++++++++++++++++++++++--- > > > > > > lib/librte_mempool/rte_mempool.h | 22 +-- > > > > > > lib/librte_ring/rte_ring.h | 6 +- > > > > > > 12 files changed, 755 insertions(+), 44 deletions(-) > > > > > > create mode 100644 examples/multi-pthread/Makefile > > > > > > create mode 100644 examples/multi-pthread/main.c > > > > > > create mode 100644 examples/multi-pthread/main.h > > > > > > > > > > > > -- > > > > > > 1.8.1.4