Date: Tue, 27 Dec 2011 16:38:04 +0100 From: Giovanni Trematerra <giovanni.trematerra@gmail.com> To: Venkatesh Srinivas <vsrinivas@dragonflybsd.org> Cc: freebsd-hackers@freebsd.org Subject: Re: Per-mount syncer threads and fanout for pagedaemon cleaning Message-ID: <CACfq090S=U-_3QA1XLNX31SD2zgAcnmG9kJrXYCvhR9Q-2JfKA@mail.gmail.com> In-Reply-To: <20111226202414.GA18713@centaur.acm.jhu.edu> References: <20111226202414.GA18713@centaur.acm.jhu.edu>
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On Mon, Dec 26, 2011 at 9:24 PM, Venkatesh Srinivas <vsrinivas@dragonflybsd.org> wrote: > Hi! > > I've been playing with two things in DragonFly that might be of interest > here. > > Thing #1 := > > First, per-mountpoint syncer threads. Currently there is a single thread, > 'syncer', which periodically calls fsync() on dirty vnodes from every mount, > along with calling vfs_sync() on each filesystem itself (via syncer vnodes). > > My patch modifies this to create syncer threads for mounts that request it. > For these mounts, vnodes are synced from their mount-specific thread rather > than the global syncer. > > The idea is that periodic fsync/sync operations from one filesystem should > not > stall or delay synchronization for other ones. > The patch was fairly simple: > http://gitweb.dragonflybsd.org/dragonfly.git/commitdiff/50e4012a4b55e1efc595db0db397b4365f08b640 > There's something WIP by attilio@ on that area. you might want to take a look at http://people.freebsd.org/~attilio/syncer_alpha_15.diff I don't know what hammerfs needs but UFS/FFS and buffer cache make a good job performance-wise and so the authors are skeptical about the boost that such a change can give. We believe that brain cycles need to be spent on other pieces of the system such as ARC and ZFS. -- Gianni
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