Messages in this thread | | | Date | Tue, 8 Jul 2003 19:06:28 +0200 | From | Herbert Poetzl <> | Subject | Re: [PATCH] Fastwalk: reduce cacheline bouncing of d_count () |
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On Tue, Jul 08, 2003 at 05:53:34PM +0100, Alan Cox wrote: > On Maw, 2003-07-08 at 17:44, Herbert Poetzl wrote: > > > Its no big problem to me since I can just back it out of -ac > > > > just curious, because I use this patch since early 2.4.20, > > are there any reasons to 'back it out of -ac' for you? > > > > anyway I totally agree that the NFS issue pointed out by > > Trond should be addressed ... > > Its high risk, its got bugs as Trond already showed and it only > helps performance on giant SMP boxes. Its all risk and no > reward. Quota updates get you working 32bit uid quota and > the interactivity stuff helps all even tho its got some > risk.
every change (if it's not a bugfix, and even those) bear a risk, what I like about the fastwalk patch is not the performance gain on giant SMP boxes, because I do not have any (unfortunately ;) but the code change from ...
if (path_init(pathname, LOOKUP_PARENT, &nd)) error = path_walk(pathname, &nd);
to error = path_lookup(pathname, LOOKUP_PARENT, &nd);
and
dentry = cached_lookup(nd->dentry, &this, 0); if (!dentry) { dentry = real_lookup(nd->dentry, &this, 0); err = PTR_ERR(dentry); if (IS_ERR(dentry)) break; }
to err = do_lookup(nd, &this, &next, &pinned, 0);
which (at least for me) is more read-/understandable ...
anyway, thanks for you answer, Herbert
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