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	Commit message (Collapse)	Author	Age	Files	Lines
*	aarch64,falkor: Ignore prefetcher hints for memmove tail	Siddhesh Poyarekar	2018-05-11	1	-18/+28
\| \| \| \| \| \| \| \| \| \| \| \| \| \| \| \| \| \|	The tail of the copy loops are unable to train the falkor hardware prefetcher because they load from a different base compared to the hot loop. In this case avoid serializing the instructions by loading them into different registers. Also peel the last iteration of the loop into the tail (and have them use different registers) since it gives better performance for medium sizes. This results in performance improvements of between 3% and 20% over the current falkor implementation for sizes between 128 bytes and 1K on the memmove-walk benchmark, thus mostly covering the regressions seen against the generic memmove. * sysdeps/aarch64/multiarch/memmove_falkor.S (__memmove_falkor): Use multiple registers to move data in loop tail.
*	Update copyright dates with scripts/update-copyrights.	Joseph Myers	2018-01-01	1	-1/+1
\| \| \| \| \| \| \|	* All files with FSF copyright notices: Update copyright dates using scripts/update-copyrights. * locale/programs/charmap-kw.h: Regenerated. * locale/programs/locfile-kw.h: Likewise.
*	aarch64: Optimized implementation of memmove for Qualcomm Falkor	Siddhesh Poyarekar	2017-10-05	1	-0/+232
	This is an optimized memmove implementation for the Qualcomm Falkor processor core. Due to the way the falkor memcpy needs to be written, code cannot be easily shared between memmove and memcpy like in case of other aarch64 memcpy implementations due to which this routine is separate. The underlying principle is the same as that of memcpy where it tries to use registers with the same lower 4 bits for fetching the same stream, thus optimizing hardware prefetcher performance. The memcpy copy loop copies 64 bytes at a time using the same register pair since that's the way to train the hardware prefetcher on the falkor core. memmove cannot quite do that since it needs to avoid overlaps, so it does the next best thing, i.e. has a 32 byte loop with a 32 byte end (prefetch a loop ahead to account for overlapping locations) with register pairs that alias so that they hit the same prefetcher. Due to this difference in loop size, they have to currently be separate implementations but efforts are on to try and get memmove to fall back into memcpy whenever it can without simply duplicating all of the code. Performance: The routine fares around 20-25% better than the generic memmove for most medium to large sizes (i.e. > 128 bytes) for the new walking memmove benchmark (memmove-walk) with an unexplained regression between 1K and 2K. The minor regression is something worth looking into for us, but the remaining gains are significant enough that we would like this included upstream as we looking into the cause for the regression. Here is a snippet of the numbers as generated from the microbenchmark by the compare_strings script. Comparisons are against __memmove_generic: Function: memmove Variant: walk __memmove_thunderx __memmove_falkor __memmove_generic ======================================================================================================================== <snip> length=16384: 12508800.00 ( 6.09%) 11486800.00 ( 13.76%) 13319600.00 length=16400: 13614200.00 ( -0.67%) 11585000.00 ( 14.33%) 13523600.00 length=16385: 13448400.00 ( 0.10%) 11732700.00 ( 12.84%) 13461200.00 length=16399: 13594100.00 ( -0.22%) 11859600.00 ( 12.57%) 13564400.00 length=16386: 13211600.00 ( 1.13%) 11503800.00 ( 13.91%) 13362400.00 length=16398: 13218600.00 ( 2.12%) 11573200.00 ( 14.30%) 13504700.00 length=16387: 13510900.00 ( -0.37%) 11744200.00 ( 12.76%) 13461300.00 length=16397: 13603700.00 ( -0.15%) 11878200.00 ( 12.55%) 13583200.00 length=16388: 13461700.00 ( -0.13%) 11558000.00 ( 14.03%) 13444100.00 length=16396: 13517500.00 ( -0.03%) 11561300.00 ( 14.45%) 13513900.00 length=16389: 13534100.00 ( 0.17%) 11756800.00 ( 13.28%) 13556900.00 length=16395: 13585600.00 ( 0.11%) 11791800.00 ( 13.30%) 13601200.00 length=16390: 13480100.00 ( -0.13%) 11685500.00 ( 13.20%) 13462100.00 length=16394: 13529900.00 ( -0.23%) 11549800.00 ( 14.43%) 13498200.00 length=16391: 13595400.00 ( -0.26%) 11768200.00 ( 13.22%) 13560600.00 length=16393: 13567000.00 ( 0.20%) 11779700.00 ( 13.35%) 13594700.00 length=32768: 71308800.00 ( -6.53%) 50220800.00 ( 24.98%) 66939200.00 length=32784: 72100800.00 (-11.55%) 50114100.00 ( 22.47%) 64636300.00 length=32769: 71767000.00 ( -7.10%) 51238400.00 ( 23.54%) 67010000.00 length=32783: 70113700.00 (-40.95%) 51129000.00 ( -2.78%) 49744400.00 length=32770: 71367600.00 ( -6.52%) 50244700.00 ( 25.01%) 67000900.00 length=32782: 64366700.00 ( 4.71%) 50101400.00 ( 25.83%) 67545600.00 length=32771: 71440100.00 ( -6.51%) 51263900.00 ( 23.57%) 67074900.00 length=32781: 66993000.00 ( 0.34%) 51108300.00 ( 23.97%) 67220300.00 length=32772: 71443900.00 (-60.50%) 50062100.00 (-12.47%) 44512600.00 length=32780: 71759100.00 ( -6.58%) 50263200.00 ( 25.35%) 67328600.00 length=32773: 71714900.00 (-33.21%) 51076600.00 ( 5.12%) 53835400.00 length=32779: 71756900.00 ( -6.56%) 51290800.00 ( 23.83%) 67337800.00 length=32774: 59689300.00 (-34.55%) 50068400.00 (-12.86%) 44363300.00 length=32778: 71847500.00 (-18.20%) 50084100.00 ( 17.61%) 60786500.00 length=32775: 71599300.00 ( -6.54%) 51278200.00 ( 23.70%) 67204800.00 length=32777: 71862900.00 (-60.85%) 51094000.00 (-14.36%) 44677900.00 length=65536: 282848000.00 ( -6.60%) 199187000.00 ( 24.93%) 265325000.00 length=65552: 243285000.00 (-41.61%) 198512000.00 (-15.54%) 171805000.00 length=65537: 255415000.00 (-23.47%) 202499000.00 ( 2.11%) 206858000.00 length=65551: 280122000.00 (-62.95%) 203349000.00 (-18.29%) 171911000.00 length=65538: 283676000.00 (-14.46%) 198368000.00 ( 19.96%) 247848000.00 length=65550: 275566000.00 (-51.76%) 198494000.00 ( -9.31%) 181581000.00 length=65539: 283699000.00 ( -6.58%) 203453000.00 ( 23.57%) 266195000.00 length=65549: 286572000.00 ( -6.65%) 202607000.00 ( 24.60%) 268712000.00 length=65540: 283710000.00 ( -6.59%) 199161000.00 ( 25.17%) 266160000.00 length=65548: 237573000.00 ( 11.48%) 198462000.00 ( 26.06%) 268395000.00 length=65541: 284150000.00 ( -6.58%) 203273000.00 ( 23.75%) 266600000.00 length=65547: 286250000.00 ( -6.70%) 202594000.00 ( 24.48%) 268263000.00 length=65542: 284167000.00 ( -6.60%) 199122000.00 ( 25.31%) 266584000.00 length=65546: 285656000.00 ( -6.59%) 198443000.00 ( 25.95%) 268002000.00 length=65543: 284600000.00 ( -6.58%) 203247000.00 ( 23.89%) 267030000.00 length=65545: 285665000.00 ( -6.40%) 202575000.00 ( 24.55%) 268472000.00 <snip> * sysdeps/aarch64/multiarch/Makefile (sysdep_routines): Add memmove_falkor. * sysdeps/aarch64/multiarch/ifunc-impl-list.c (__libc_ifunc_impl_list): Likewise. * sysdeps/aarch64/multiarch/memmove.c: Likewise. * sysdeps/aarch64/multiarch/memmove_falkor.S: New file.

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The tail of the copy loops are unable to train the falkor hardware prefetcher because they load from a different base compared to the hot loop. In this case avoid serializing the instructions by loading them into different registers. Also peel the last iteration of the loop into the tail (and have them use different registers) since it gives better performance for medium sizes. This results in performance improvements of between 3% and 20% over the current falkor implementation for sizes between 128 bytes and 1K on the memmove-walk benchmark, thus mostly covering the regressions seen against the generic memmove. * sysdeps/aarch64/multiarch/memmove_falkor.S (__memmove_falkor): Use multiple registers to move data in loop tail.

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* All files with FSF copyright notices: Update copyright dates using scripts/update-copyrights. * locale/programs/charmap-kw.h: Regenerated. * locale/programs/locfile-kw.h: Likewise.

This is an optimized memmove implementation for the Qualcomm Falkor processor core. Due to the way the falkor memcpy needs to be written, code cannot be easily shared between memmove and memcpy like in case of other aarch64 memcpy implementations due to which this routine is separate. The underlying principle is the same as that of memcpy where it tries to use registers with the same lower 4 bits for fetching the same stream, thus optimizing hardware prefetcher performance. The memcpy copy loop copies 64 bytes at a time using the same register pair since that's the way to train the hardware prefetcher on the falkor core. memmove cannot quite do that since it needs to avoid overlaps, so it does the next best thing, i.e. has a 32 byte loop with a 32 byte end (prefetch a loop ahead to account for overlapping locations) with register pairs that alias so that they hit the same prefetcher. Due to this difference in loop size, they have to currently be separate implementations but efforts are on to try and get memmove to fall back into memcpy whenever it can without simply duplicating all of the code. Performance: The routine fares around 20-25% better than the generic memmove for most medium to large sizes (i.e. > 128 bytes) for the new walking memmove benchmark (memmove-walk) with an unexplained regression between 1K and 2K. The minor regression is something worth looking into for us, but the remaining gains are significant enough that we would like this included upstream as we looking into the cause for the regression. Here is a snippet of the numbers as generated from the microbenchmark by the compare_strings script. Comparisons are against __memmove_generic: Function: memmove Variant: walk __memmove_thunderx __memmove_falkor __memmove_generic ======================================================================================================================== <snip> length=16384: 12508800.00 ( 6.09%) 11486800.00 ( 13.76%) 13319600.00 length=16400: 13614200.00 ( -0.67%) 11585000.00 ( 14.33%) 13523600.00 length=16385: 13448400.00 ( 0.10%) 11732700.00 ( 12.84%) 13461200.00 length=16399: 13594100.00 ( -0.22%) 11859600.00 ( 12.57%) 13564400.00 length=16386: 13211600.00 ( 1.13%) 11503800.00 ( 13.91%) 13362400.00 length=16398: 13218600.00 ( 2.12%) 11573200.00 ( 14.30%) 13504700.00 length=16387: 13510900.00 ( -0.37%) 11744200.00 ( 12.76%) 13461300.00 length=16397: 13603700.00 ( -0.15%) 11878200.00 ( 12.55%) 13583200.00 length=16388: 13461700.00 ( -0.13%) 11558000.00 ( 14.03%) 13444100.00 length=16396: 13517500.00 ( -0.03%) 11561300.00 ( 14.45%) 13513900.00 length=16389: 13534100.00 ( 0.17%) 11756800.00 ( 13.28%) 13556900.00 length=16395: 13585600.00 ( 0.11%) 11791800.00 ( 13.30%) 13601200.00 length=16390: 13480100.00 ( -0.13%) 11685500.00 ( 13.20%) 13462100.00 length=16394: 13529900.00 ( -0.23%) 11549800.00 ( 14.43%) 13498200.00 length=16391: 13595400.00 ( -0.26%) 11768200.00 ( 13.22%) 13560600.00 length=16393: 13567000.00 ( 0.20%) 11779700.00 ( 13.35%) 13594700.00 length=32768: 71308800.00 ( -6.53%) 50220800.00 ( 24.98%) 66939200.00 length=32784: 72100800.00 (-11.55%) 50114100.00 ( 22.47%) 64636300.00 length=32769: 71767000.00 ( -7.10%) 51238400.00 ( 23.54%) 67010000.00 length=32783: 70113700.00 (-40.95%) 51129000.00 ( -2.78%) 49744400.00 length=32770: 71367600.00 ( -6.52%) 50244700.00 ( 25.01%) 67000900.00 length=32782: 64366700.00 ( 4.71%) 50101400.00 ( 25.83%) 67545600.00 length=32771: 71440100.00 ( -6.51%) 51263900.00 ( 23.57%) 67074900.00 length=32781: 66993000.00 ( 0.34%) 51108300.00 ( 23.97%) 67220300.00 length=32772: 71443900.00 (-60.50%) 50062100.00 (-12.47%) 44512600.00 length=32780: 71759100.00 ( -6.58%) 50263200.00 ( 25.35%) 67328600.00 length=32773: 71714900.00 (-33.21%) 51076600.00 ( 5.12%) 53835400.00 length=32779: 71756900.00 ( -6.56%) 51290800.00 ( 23.83%) 67337800.00 length=32774: 59689300.00 (-34.55%) 50068400.00 (-12.86%) 44363300.00 length=32778: 71847500.00 (-18.20%) 50084100.00 ( 17.61%) 60786500.00 length=32775: 71599300.00 ( -6.54%) 51278200.00 ( 23.70%) 67204800.00 length=32777: 71862900.00 (-60.85%) 51094000.00 (-14.36%) 44677900.00 length=65536: 282848000.00 ( -6.60%) 199187000.00 ( 24.93%) 265325000.00 length=65552: 243285000.00 (-41.61%) 198512000.00 (-15.54%) 171805000.00 length=65537: 255415000.00 (-23.47%) 202499000.00 ( 2.11%) 206858000.00 length=65551: 280122000.00 (-62.95%) 203349000.00 (-18.29%) 171911000.00 length=65538: 283676000.00 (-14.46%) 198368000.00 ( 19.96%) 247848000.00 length=65550: 275566000.00 (-51.76%) 198494000.00 ( -9.31%) 181581000.00 length=65539: 283699000.00 ( -6.58%) 203453000.00 ( 23.57%) 266195000.00 length=65549: 286572000.00 ( -6.65%) 202607000.00 ( 24.60%) 268712000.00 length=65540: 283710000.00 ( -6.59%) 199161000.00 ( 25.17%) 266160000.00 length=65548: 237573000.00 ( 11.48%) 198462000.00 ( 26.06%) 268395000.00 length=65541: 284150000.00 ( -6.58%) 203273000.00 ( 23.75%) 266600000.00 length=65547: 286250000.00 ( -6.70%) 202594000.00 ( 24.48%) 268263000.00 length=65542: 284167000.00 ( -6.60%) 199122000.00 ( 25.31%) 266584000.00 length=65546: 285656000.00 ( -6.59%) 198443000.00 ( 25.95%) 268002000.00 length=65543: 284600000.00 ( -6.58%) 203247000.00 ( 23.89%) 267030000.00 length=65545: 285665000.00 ( -6.40%) 202575000.00 ( 24.55%) 268472000.00 <snip> * sysdeps/aarch64/multiarch/Makefile (sysdep_routines): Add memmove_falkor. * sysdeps/aarch64/multiarch/ifunc-impl-list.c (__libc_ifunc_impl_list): Likewise. * sysdeps/aarch64/multiarch/memmove.c: Likewise. * sysdeps/aarch64/multiarch/memmove_falkor.S: New file.