Date: Fri, 07 Mar 2008 07:40:28 -0800 From: Kirk McKusick <mckusick@mckusick.com> To: John Baldwin <jhb@freebsd.org> Cc: arch@freebsd.org Subject: Re: Getting rid of the static msleep priority boost Message-ID: <200803071540.m27FeSU6096030@chez.mckusick.com>
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> From: John Baldwin <jhb@freebsd.org> > To: Jeff Roberson <jroberson@chesapeake.net> > Date: Fri, 7 Mar 2008 08:42:37 -0500 > Cc: arch@freebsd.org > Subject: Re: Getting rid of the static msleep priority boost > > On Friday 07 March 2008 07:16:30 am Jeff Roberson wrote: > > Hello, > > > > I've been studying some problems with recent scheduler improvements that > > help a lot on some workloads and hurt on others. I've tracked the problem > > down to static priority boosts handed out by msleep/cv_broadcastpri. > > ... > > ... > > This change allows the decision on priority boost to be a scheduler > decision to ignore it (so 4BSD could continue to do what it does now, > but ULE may ignore it, or ignore certain levels, etc.) > > -- > John Baldwin I strongly agree with John's suggestion. The 4BSD scheduler will continue to have its historic behavior (which was `tuned' by careful selection of priority boosts) while more sophisticated schedulers like ULE will be able to use/ignore the priority boosts based on their better knowledge of system behavior. Kirk McKusick
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