From mboxrd@z Thu Jan 1 00:00:00 1970 From: Bill Davidsen Subject: Re: 2.6.24-rc6 reproducible raid5 hang Date: Thu, 10 Jan 2008 15:28:30 -0500 Message-ID: <47867FEE.8070704@tmr.com> References: <1199903330.18882.7.camel@dwillia2-linux.ch.intel.com> <18309.25170.258730.225322@notabene.brown> <18309.38832.518580.235804@notabene.brown> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <18309.38832.518580.235804@notabene.brown> Sender: linux-raid-owner@vger.kernel.org To: Neil Brown Cc: Dan Williams , dean gaudet , linux-raid@vger.kernel.org List-Id: linux-raid.ids Neil Brown wrote: > On Wednesday January 9, dan.j.williams@intel.com wrote: > >> On Jan 9, 2008 5:09 PM, Neil Brown wrote: >> >>> On Wednesday January 9, dan.j.williams@intel.com wrote: >>> >>> Can you test it please? >>> >> This passes my failure case. >> > > Thanks! > > >>> Does it seem reasonable? >>> >> What do you think about limiting the number of stripes the submitting >> thread handles to be equal to what it submitted? If I'm a stripe that >> only submits 1 stripe worth of work should I get stuck handling the >> rest of the cache? >> > > Dunno.... > Someone has to do the work, and leaving it all to raid5d means that it > all gets done on one CPU. > I expect that most of the time the queue of ready stripes is empty so > make_request will mostly only handle it's own stripes anyway. > The times that it handles other thread's stripes will probably balance > out with the times that other threads handle this threads stripes. > > So I'm incline to leave it as "do as much work as is available to be > done" as that is simplest. But I can probably be talked out of it > with a convincing argument.... > How about "it will perform better (defined as faster) during conditions of unusual i/o activity?" Is that a convincing argument to use your solution as offered? How about "complexity and maintainability are a zero-sum problem?" -- Bill Davidsen "Woe unto the statesman who makes war without a reason that will still be valid when the war is over..." Otto von Bismark