> -----Original Message----- > From: Ananyev, Konstantin > Sent: Tuesday, January 27, 2015 2:29 AM > To: Wang, Zhihong; Richardson, Bruce; Marc Sune > Cc: dev at dpdk.org > Subject: RE: [dpdk-dev] [PATCH 0/4] DPDK memcpy optimization > > Hi Zhihong, > > > -----Original Message----- > > From: dev [mailto:dev-bounces at dpdk.org] On Behalf Of Wang, Zhihong > > Sent: Friday, January 23, 2015 6:52 AM > > To: Richardson, Bruce; Marc Sune > > Cc: dev at dpdk.org > > Subject: Re: [dpdk-dev] [PATCH 0/4] DPDK memcpy optimization > > > > > > > > > -----Original Message----- > > > From: dev [mailto:dev-bounces at dpdk.org] On Behalf Of Bruce > > > Richardson > > > Sent: Wednesday, January 21, 2015 9:26 PM > > > To: Marc Sune > > > Cc: dev at dpdk.org > > > Subject: Re: [dpdk-dev] [PATCH 0/4] DPDK memcpy optimization > > > > > > 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 at 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 at tuxdriver.com] > > > > >>>>>>>Sent: Monday, January 19, 2015 9:02 PM > > > > >>>>>>>To: Wang, Zhihong > > > > >>>>>>>Cc: dev at dpdk.org > > > > >>>>>>>Subject: Re: [dpdk-dev] [PATCH 0/4] DPDK memcpy > > > > >>>>>>>optimization > > > > >>>>>>> > > > > >>>>>>>On Mon, Jan 19, 2015 at 09:53:30AM +0800, > > > > >>>>>>>zhihong.wang at 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 > > > > Since we're clear now that the long compile time is mainly caused by too > many inline function calls, I think it's okay not to do this. > > Would you agree? > > Actually I wonder, if instead of: > > + switch (srcofs) { > + case 0x01: MOVEUNALIGNED_LEFT47(dst, src, n, 0x01); break; > + case 0x02: MOVEUNALIGNED_LEFT47(dst, src, n, 0x02); break; > + case 0x03: MOVEUNALIGNED_LEFT47(dst, src, n, 0x03); break; > + case 0x04: MOVEUNALIGNED_LEFT47(dst, src, n, 0x04); break; > + case 0x05: MOVEUNALIGNED_LEFT47(dst, src, n, 0x05); break; > + case 0x06: MOVEUNALIGNED_LEFT47(dst, src, n, 0x06); break; > + case 0x07: MOVEUNALIGNED_LEFT47(dst, src, n, 0x07); break; > + case 0x08: MOVEUNALIGNED_LEFT47(dst, src, n, 0x08); break; > + case 0x09: MOVEUNALIGNED_LEFT47(dst, src, n, 0x09); break; > + case 0x0A: MOVEUNALIGNED_LEFT47(dst, src, n, 0x0A); break; > + case 0x0B: MOVEUNALIGNED_LEFT47(dst, src, n, 0x0B); break; > + case 0x0C: MOVEUNALIGNED_LEFT47(dst, src, n, 0x0C); break; > + case 0x0D: MOVEUNALIGNED_LEFT47(dst, src, n, 0x0D); break; > + case 0x0E: MOVEUNALIGNED_LEFT47(dst, src, n, 0x0E); break; > + case 0x0F: MOVEUNALIGNED_LEFT47(dst, src, n, 0x0F); break; > + default:; > + } > > We'll just do: > MOVEUNALIGNED_LEFT47(dst, src, n, srcofs); > > That should reduce size of the generated code quite a bit, wouldn't it? > From other side MOVEUNALIGNED_LEFT47() is pretty big chunk, so > performance difference having offset value in a register vs immediate value > shouldn't be significant. > > Konstantin > > > > > Zhihong (John)
Hey Konstantin, We have to use switch here because PALIGNR requires the shift count to be an 8-bit immediate. Zhihong (John)
