Date: Tue, 22 Jan 2008 20:27:07 +0200 From: Stefan Lambrev <stefan.lambrev@moneybookers.com> To: Kris Kennaway <kris@FreeBSD.org> Cc: =?UTF-8?B?RGFnLUVybGluZyBTbcO4cmdyYXY=?= <des@des.no>, freebsd-hackers@FreeBSD.org Subject: Re: gettimeofday() in hping Message-ID: <4796357B.9020508@moneybookers.com> In-Reply-To: <479621BE.2060907@FreeBSD.org> References: <4795CC13.7080601@moneybookers.com> <868x2i3v8d.fsf@ds4.des.no> <864pd63v2h.fsf@ds4.des.no> <4795FE54.9090606@moneybookers.com> <86lk6i0vzk.fsf@ds4.des.no> <479605E2.6070709@moneybookers.com> <479621BE.2060907@FreeBSD.org>
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Greetings, Kris Kennaway wrote: > Stefan Lambrev wrote: >> Hi, >> >> Dag-Erling Sm=C3=B8rgrav wrote: >>> Stefan Lambrev <stefan.lambrev@moneybookers.com> writes: >>> =20 >>>> I tested all different combination. The performance change is almost= >>>> invisible (100-200KB/s), and can't be compared with the performance >>>> boost that TSC gain over ACPI-fast timecounter. Unfortunately TSC >>>> doesn't play nice with power saving modes. >>>> =20 >>> >>> This will vary greatly from machine to machine, depending on the exac= t >>> hardware and the ACPI BIOS. >>> >>> More modern machines have an HPET timer which is supposedly faster th= an >>> ACPI yet more reliable than TSC. >>> >>> DES >>> =20 >> I do not have HEPT on the servers that I test, but simple test on my=20 >> laptop shows >> that hping can generate with ACPI-fast ~4MB/s traffic, 5MB/s with HPET= >> and 8MB/s with TSC. I didn't check dummy time counter. >> Also I noticed that there is a kern.timecounter.tc.XXX.quality (read=20 >> only). >> Can this be used to reduce quality and speed up performance? > > No, they are meaningless values only used to rank the time counters=20 > and choose one at boot. > > You should use hwpmc to verify where the application is really=20 > spending time, since gettimeofday doesn't seem to account for it all. pmc: Unknown Intel CPU. module_register_init: MOD_LOAD (hwpmc, 0xffffffff8029906d,=20 0xffffffff8054c500) error 78 What was the other way to do this profiling? Can ktrace help? Here is sample of kdump -R: 7501 hping 0.000013 RET sendto 40/0x28 7501 hping 0.000019 CALL sigaction(SIGALRM,0xbfbfe8a8,0xbfbfe890) 7501 hping 0.000014 RET sigaction 0 7501 hping 0.000013 CALL setitimer(0,0xbfbfe8b4,0xbfbfe8a4) 7501 hping 0.000016 RET setitimer 0 7501 hping 0.000017 CALL gettimeofday(0xbfbfe870,0) 7501 hping 0.000022 RET gettimeofday 0 7501 hping 0.000015 CALL gettimeofday(0xbfbfe868,0) 7501 hping 0.000016 RET gettimeofday 0 7501 hping 0.000015 CALL sendto(0x3,0x28317040,0x28,0,0x8067d80,0x1= 0) 7501 hping 0.000026 GIO fd 3 wrote 40 bytes --=20 Best Wishes, Stefan Lambrev ICQ# 24134177
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