Date: Thu, 19 Aug 2010 15:38:54 +0200 From: =?utf-8?Q?Dag-Erling_Sm=C3=B8rgrav?= <des@des.no> To: Gabor Kovesdan <gabor@FreeBSD.org> Cc: delphij@FreeBSD.org, Dimitry Andric <dimitry@andric.com>, Doug Barton <dougb@FreeBSD.org>, core@FreeBSD.org, current@FreeBSD.org Subject: Re: Official request: Please make GNU grep the default Message-ID: <86aaoirac1.fsf@ds4.des.no> References: <4C6505A4.9060203@FreeBSD.org> <4C6C1CFE.6060900@FreeBSD.org>
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Gabor Kovesdan <gabor@FreeBSD.org> writes: > I've just committed a patch with the kind help of Dimitry Andric, > which gives BSD grep a huge performance boost. The performance is now > almost comparable to GNU grep. Not quite, as Doug pointed out. I don't know what benchmark you're using, but I'm using a greatly simplified variant of Doug's: % time sh -c 'for n in $(jot 1000) ; do /usr/obj/usr/src/usr.bin/grep/grep = -q "^xfce4-wm" /usr/ports/INDEX-9 ; done'=20 sh -c 13.57s user 7.06s system 99% cpu 20.783 total % time sh -c 'for n in $(jot 1000) ; do /usr/obj/usr/src/gnu/usr.bin/grep/g= rep -q "^xfce4-wm" /usr/ports/INDEX-9 ; done' sh -c 7.98s user 7.47s system 100% cpu 15.424 total The bottleneck is now in quite an unexpected location: % cumulative self self total=20=20=20=20=20=20=20=20= =20=20=20 time seconds seconds calls ms/call ms/call name=20=20=20=20 38.8 0.03 0.03 12717 0.00 0.00 memchr [5] 35.6 0.07 0.03 395 0.08 0.08 _read [6] 16.4 0.08 0.01 0 100.00% _mcount [7] 1.7 0.08 0.00 12362 0.00 0.00 memset [9] 1.5 0.08 0.00 0 100.00% .mcount (110) 1.5 0.08 0.00 0 43.41% re_search_internal [8] 0.8 0.08 0.00 820 0.00 0.00 memcpy [12] 0.6 0.09 0.00 37045 0.00 0.00 free [13] 0.6 0.09 0.00 12332 0.00 0.01 grep_fgetln [4] 0.6 0.09 0.00 1 0.49 66.27 procfile [3] 0.4 0.09 0.00 0 100.00% re_string_construct_c= ommon [26] 0.3 0.09 0.00 1 0.25 0.34 _Read_RuneMagi [27] 0.1 0.09 0.00 261 0.00 0.00 arena_avail_comp [39] 0.1 0.09 0.00 155 0.00 0.00 arena_malloc [24] 0.1 0.09 0.00 153 0.00 0.00 arena_bin_malloc_easy= [40] 0.1 0.09 0.00 54 0.00 0.00 arena_avail_tree_inse= rt [35] 0.1 0.09 0.00 5 0.02 0.02 arena_purge [37] 0.1 0.09 0.00 3 0.04 0.44 setlocale [10] 0.1 0.09 0.00 1 0.12 0.46 __wrap_setrunelocale = [21] 0.1 0.09 0.00 0 21.76% re_string_destruct [1= 4] 0.1 0.09 0.00 0 100.00% regexec [38] The culprit seems to be the first memchr() in grep_fgetln(). For some reason, even with -O2, it is not inlined: % echo "disassemble grep_fgetln" | gdb -q -batch -x /dev/stdin /usr/obj/usr= /src/usr.bin/grep/grep | grep memchr 0x000000000040291e <grep_fgetln+244>: callq 0x40176c <memchr> 0x00000000004029fa <grep_fgetln+464>: callq 0x40176c <memchr> DES --=20 Dag-Erling Sm=C3=B8rgrav - des@des.no
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