> -----Original Message----- > From: dev [mailto:dev-bounces at dpdk.org] On Behalf Of Wang, Zhihong > Sent: Wednesday, January 21, 2015 3:44 AM > To: Richardson, Bruce; Neil Horman > Cc: dev at dpdk.org > Subject: Re: [dpdk-dev] [PATCH 0/4] DPDK memcpy optimization > > > > > -----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.
We use instrincts and inlining in many other places too. Why it suddenly became a problem here? Konstantin > 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) > > >
