Date: Wed, 30 Sep 2009 13:09:40 -0700 From: "Matthew Fleming" <matthew.fleming@isilon.com> To: "Kostik Belousov" <kostikbel@gmail.com>, "Zachary Loafman" <zml@freebsd.org> Cc: svn-src-stable@freebsd.org, svn-src-stable-7@freebsd.org Subject: RE: svn commit: r197652 - stable/7/sys/kern Message-ID: <06D5F9F6F655AD4C92E28B662F7F853E03171462@seaxch09.desktop.isilon.com> In-Reply-To: <20090930195254.GK3130@deviant.kiev.zoral.com.ua> References: <200909301940.n8UJep9X024249@svn.freebsd.org> <20090930195254.GK3130@deviant.kiev.zoral.com.ua>
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> > sched_ule in stable/7 has a bug (introduced in r180607) where a thread > > that is running often will appear to not be running much at all. > Why is this not a problem on HEAD ? I can't say definitively there's not a bug on HEAD of some kind, but when I ran a CPU hog and looked at the output of top(1), on HEAD the hog was listed as near 100%, and on stable/7 it was listed as 0% after a few seconds for the system to settle. Since the code looked at least somewhat different and the bug did not reproduce on HEAD, I assumed it was only a problem on stable/7. I had to run HEAD code in a virtual machine, perhaps this made a difference? >From a code inspection standpoint, I don't see anything obvious. On stable/7, the set of ts_ltick in tdq_runq_rem() appears to be the reason a cpu hog was not getting incremented by sched_tick(). On HEAD this set is moved to sched_choose(). Thanks, matthew
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