Date: Tue, 2 Jul 2013 19:12:55 +0200 From: Attilio Rao <attilio@freebsd.org> To: Andriy Gapon <avg@freebsd.org> Cc: svn-src-head@freebsd.org, svn-src-all@freebsd.org, src-committers@freebsd.org, Konstantin Belousov <kib@freebsd.org> Subject: Re: should_yield problem [Was: svn commit: r251322 - head/sys/kern] Message-ID: <CAJ-FndD5tCxe-L8V73MFtk_4xr0Wq3MHasKY4O_tcA3uYouKAw@mail.gmail.com> In-Reply-To: <51D30463.50608@FreeBSD.org> References: <201306031736.r53Hain5093431@svn.freebsd.org> <51D30463.50608@FreeBSD.org>
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On Tue, Jul 2, 2013 at 6:48 PM, Andriy Gapon <avg@freebsd.org> wrote: > on 03/06/2013 20:36 Konstantin Belousov said the following: >> Author: kib >> Date: Mon Jun 3 17:36:43 2013 >> New Revision: 251322 >> URL: http://svnweb.freebsd.org/changeset/base/251322 >> >> Log: >> Be more generous when donating the current thread time to the owner of >> the vnode lock while iterating over the free vnode list. Instead of >> yielding, pause for 1 tick. The change is reported to help in some >> virtualized environments. > > Kostik, > > I've just run into a problem where word "generous" does not seem to be > applicable at all unless I am mistaken about how the code works. While "ticks" is signed it is used as an unsigned int. td_swvolticks is always derived by ticks, which again will always be used as an unisgned and then the subtractions among the 2 will be consistent. Attilio -- Peace can only be achieved by understanding - A. Einstein
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