From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: by sourceware.org (Postfix, from userid 1944) id 763633850404; Thu, 21 Jan 2021 16:45:19 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 763633850404 Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit From: Szabolcs Nagy To: glibc-cvs@sourceware.org Subject: [glibc] aarch64: revert memcpy optimze for kunpeng to avoid performance degradation X-Act-Checkin: glibc X-Git-Author: Shuo Wang X-Git-Refname: refs/heads/master X-Git-Oldrev: 2682695e5c7acf1e60dd3b5c3a14d4e82416262c X-Git-Newrev: 28f2ce27722d890a884cc7fa2f6d2bc0cb418f26 Message-Id: <20210121164519.763633850404@sourceware.org> Date: Thu, 21 Jan 2021 16:45:19 +0000 (GMT) X-BeenThere: glibc-cvs@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Glibc-cvs mailing list List-Unsubscribe: , List-Archive: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 21 Jan 2021 16:45:19 -0000 https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=28f2ce27722d890a884cc7fa2f6d2bc0cb418f26 commit 28f2ce27722d890a884cc7fa2f6d2bc0cb418f26 Author: Shuo Wang Date: Wed Jan 20 15:20:44 2021 +0800 aarch64: revert memcpy optimze for kunpeng to avoid performance degradation In commit 863d775c481704baaa41855fc93e5a1ca2dc6bf6, kunpeng920 is added to default memcpy version, however, there is performance degradation when the copy size is some large bytes, eg: 100k. This is the result, tested in glibc-2.28: before backport after backport Performance improvement memcpy_1k 0.005 0.005 0.00% memcpy_10k 0.032 0.029 10.34% memcpy_100k 0.356 0.429 -17.02% memcpy_1m 7.470 11.153 -33.02% This is the demo #include "stdio.h" #include "string.h" #include "stdlib.h" char a[1024*1024] = {12}; char b[1024*1024] = {13}; int main(int argc, char *argv[]) { int i = atoi(argv[1]); int j; int size = atoi(argv[2]); for (j = 0; j < i; j++) memcpy(b, a, size*1024); return 0; } # gcc -g -O0 memcpy.c -o memcpy # time taskset -c 10 ./memcpy 100000 1024 Co-authored-by: liqingqing Diff: --- sysdeps/aarch64/multiarch/memcpy.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/sysdeps/aarch64/multiarch/memcpy.c b/sysdeps/aarch64/multiarch/memcpy.c index 27259d3386..0e0a5cbcfb 100644 --- a/sysdeps/aarch64/multiarch/memcpy.c +++ b/sysdeps/aarch64/multiarch/memcpy.c @@ -37,7 +37,7 @@ extern __typeof (__redirect_memcpy) __memcpy_falkor attribute_hidden; libc_ifunc (__libc_memcpy, (IS_THUNDERX (midr) ? __memcpy_thunderx - : (IS_FALKOR (midr) || IS_PHECDA (midr) || IS_KUNPENG920 (midr) + : (IS_FALKOR (midr) || IS_PHECDA (midr) ? __memcpy_falkor : (IS_THUNDERX2 (midr) || IS_THUNDERX2PA (midr) ? __memcpy_thunderx2