Date: Mon, 9 Apr 2012 11:08:50 -0700 (PDT) From: Sushanth Rai <sushanth_rai@yahoo.com> To: John Baldwin <jhb@freebsd.org> Cc: freebsd-hackers@freebsd.org Subject: Re: Startvation of realtime piority threads Message-ID: <1333994930.58509.YahooMailClassic@web180004.mail.gq1.yahoo.com> In-Reply-To: <201204091217.05561.jhb@freebsd.org>
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I'm on 7.2. sched_sleep() on 7.2 just records the sleep time. That's why I though _sleep might the right place to do the check. Thanks, Sushanth --- On Mon, 4/9/12, John Baldwin <jhb@freebsd.org> wrote: > From: John Baldwin <jhb@freebsd.org> > Subject: Re: Startvation of realtime piority threads > To: "Sushanth Rai" <sushanth_rai@yahoo.com> > Cc: freebsd-hackers@freebsd.org > Date: Monday, April 9, 2012, 9:17 AM > On Thursday, April 05, 2012 9:08:24 > pm Sushanth Rai wrote: > > I understand the downside of badly written realtime > app. In my case > application runs in userspace without making much syscalls > and by all means it > is a well behaved application. Yes, I can wire memory, > change the application > to use mutex instead of spinlock and those changes should > help but they are > still working around the problem. I still believe kernel > should not lower the > realtime priority when blocking on resources. This can lead > to priority > inversion, especially since these threads run at fixed > priorities and kernel > doesn't muck with them. > > > > As you suggested _sleep() should not adjust the > priorities for realtime > threads. > > Hmm, sched_sleep() for both SCHED_4BSD and SCHED_ULE already > does the right > thing here in HEAD. > > if (PRI_BASE(td->td_pri_class) != > PRI_TIMESHARE) > return; > > Which OS version did you see this on? > > -- > John Baldwin >
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