Date: Fri, 29 Jul 2005 12:03:37 +0200 From: Suleiman Souhlal <ssouhlal@FreeBSD.org> To: Joseph Koshy <jkoshy@FreeBSD.org> Cc: Martin Cracauer <cracauer@cons.org>, freebsd-current@FreeBSD.org Subject: Re: PMC (performance counters) problems - kernel panic in 6-beta1 Message-ID: <63730E21-8766-4A87-8878-EACE167E64C5@FreeBSD.org> In-Reply-To: <20050729031107.C2FD616A41F@hub.freebsd.org> References: <20050729031107.C2FD616A41F@hub.freebsd.org>
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Hi, On Jul 29, 2005, at 5:11 AM, Joseph Koshy wrote: > > > >> Another question, what is the difference of -s versus -S and -p >> versus >> -P, respectively? >> > > -S and -P turn on sampling. -S does 'whole system' sampling. -P is > process specific (i.e., the counters only count when the target > process(es) > are running). > > So: > > # pmcstat -S instructions -O /tmp/foo.out > > will collect samples. > > # pmcstat -g -R /tmp/foo.out > > will convert the sample log to gprof(1) compatible 'gmon.out' files. > > Sampling on the AMD64 requires a patch to current [I'll commit it > shortly]. Is sampling supposed to work on i386? Because it doesn't seem to collect anything. Counting works fine, on the other hand. # pmcstat -P instructions -O sample.out -d fsck_ffs /usr > /dev/null & [1] + done pmcstat -P instructions -O sample.out -d fsck_ffs / usr > /dev/null # pmcstat -R sample.out -g # ls k7-retired-instructions # -- Suleiman Souhlal | ssouhlal@vt.edu The FreeBSD Project | ssouhlal@FreeBSD.org
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