Date: Tue, 12 Dec 2006 13:11:36 +0900 From: "Adrian Chadd" <adrian@freebsd.org> To: "Joseph Koshy" <joseph.koshy@gmail.com> Cc: freebsd-hackers@freebsd.org Subject: Re: pmcstat and squid Message-ID: <d763ac660612112011m4b40efe3ud32983291906f724@mail.gmail.com> In-Reply-To: <84dead720612112006r5573a04fge2664ffe3a93f796@mail.gmail.com> References: <d763ac660612111955p6dc85a8ufca9ff3b78e3f376@mail.gmail.com> <84dead720612112006r5573a04fge2664ffe3a93f796@mail.gmail.com>
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On 12/12/06, Joseph Koshy <joseph.koshy@gmail.com> wrote: > > I can think of one of two scenarios: > > 1) the squid process was in the kernel when the > samples got taken. This could happen if the > process was say in select() handling all the time. > 2) There a bug in my process handling code that is > being triggered (hwpmc undercounts process-mode > samples), and samples are being missed. I can't imagine why Squid would suddenly be in kernel mode all the time. In fact, its in kernel space about 20% of the time under this workload (with another 30% spent in interrupts.) Here's the output from my latest attempt: jacinta# pmcstat -S instructions -O samples.out ^Cjacinta# ls -l total 89650 -rw-r--r-- 1 root wheel 576 Dec 12 03:52 1 -rw-r--r-- 1 root wheel 91719744 Dec 12 04:10 samples.out jacinta# pmcstat -R samples.out -g jacinta# cd k7-retired-instructions/ jacinta# ls kernel.gmon ld-elf.so.1.gmon libc.so.6.gmon jacinta# ls -l total 3116 -rw-r--r-- 1 root wheel 2704268 Dec 12 04:10 kernel.gmon -rw-r--r-- 1 root wheel 59474 Dec 12 04:10 ld-elf.so.1.gmon -rw-r--r-- 1 root wheel 372962 Dec 12 04:10 libc.so.6.gmon Squid is running but there's no profiling information for it still.. Scarily, on this Athlon 1800XP: % cumulative self self total time seconds seconds calls ms/call ms/call name 5.1 45254.00 45254.00 SHA256_Transform [1] 4.0 81184.00 35930.00 tcp_input [2] 3.8 114879.00 33695.00 tcp_output [3] 2.8 139645.00 24766.00 critical_exit [4] 2.5 162199.00 22554.00 bus_dmamap_load_mbuf_sg [5] 2.3 182415.00 20216.00 generic_bzero [6] 2.1 201156.00 18741.00 kqueue_register [7] The kernel spends quite a bit of time in SHA256_Transform; I wonder if it has to do with the sheer volume of TCP connections I'm making..
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