Date: Fri, 16 Aug 2013 11:17:20 -0700 From: Colin Percival <cperciva@freebsd.org> To: Ivan Voras <ivoras@freebsd.org> Cc: svn-src-head@freebsd.org, svn-src-all@freebsd.org, src-committers@freebsd.org Subject: Re: svn commit: r254380 - in head/sys: kern sys Message-ID: <520E6CB0.9000100@freebsd.org> In-Reply-To: <CAF-QHFXAJvUANiMt3MpOM1WZoqHQcMuGesBR3LL6benqrYRW5w@mail.gmail.com> References: <201308152019.r7FKJI0H095440@svn.freebsd.org> <CAF-QHFXXxQC69djweY7mK1tjbTSNxTPh1=-FxUeyz1nr_0WdHQ@mail.gmail.com> <520D3AD8.4090207@freebsd.org> <CAF-QHFXs11NqBMDWaHmUb%2B42z-MXh6yR3=1q92YoYNio1K3B0Q@mail.gmail.com> <520D49EB.9060308@freebsd.org> <CAF-QHFXAJvUANiMt3MpOM1WZoqHQcMuGesBR3LL6benqrYRW5w@mail.gmail.com>
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On 08/16/13 02:38, Ivan Voras wrote: >> We have a single-writer / multiple-readers lock on *any particular byte* >> of a vnode. The rangelock code is what keeps track of this, and the >> locking contention I was reducing was in the rangelock bookkeeping. > > So, for example, if multiple processes or multiple threads read or > write a file somewhat unintelligently (a small file, operations on the > whole file, like in blogbench), they will effectively content for the > byte 0, right? There can be multiple reads or one write, so yes there would be contention in that case. -- Colin Percival Security Officer Emeritus, FreeBSD | The power to serve Founder, Tarsnap | www.tarsnap.com | Online backups for the truly paranoid
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