Messages in this thread | | | From | Jeff Layton <> | Date | Fri, 12 Dec 2014 06:54:08 -0500 | Subject | Re: [PATCH v2 00/16] nfsd/sunrpc: add support for a workqueue-based nfsd |
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On Fri, 12 Dec 2014 03:02:06 +0000 Al Viro <viro@ZenIV.linux.org.uk> wrote:
> On Thu, Dec 11, 2014 at 06:29:37PM -0800, Linus Torvalds wrote: > > On Thu, Dec 11, 2014 at 6:12 PM, Al Viro <viro@zeniv.linux.org.uk> wrote: > > > > > > Linus, do you see any problems with the following patch (against the mainline)? > > > > Not concpetually, but create_kthread() uses CLONE_FS, and I don't > > think it's just umask that things like nfsd want to avoid sharing. > > What about all the *other* fields? > > > > Just as an example: even if all the threads actually end up all having > > the same global root, what about contention on 'fs->lock'? > > > > I have *not* looked at the details, and maybe there's some reason I'm > > completely off, but it worries me. > > Umm... I would be very surprised if it turned out to be a problem. > nfsd really doesn't give a fuck about its cwd and root - not in the > thread side of things. And (un)exporting is (a) not on a hot path > and (b) not done from a kernel thread anyway. fh_to_dentry and friends > doesn't care about root/cwd, etc. > > I don't see anything that could cause that kind of issues.
I like the change overall -- it would certainly make my patch series simpler, but what about pathwalking? We do take the fs->lock in unlazy_walk. Is it possible we'd end up with more contention there?
-- Jeff Layton <jlayton@primarydata.com>
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