From: Christopher Lameter <cl@linux.com>
To: Al Viro <viro@zeniv.linux.org.uk>
Cc: "Tobin C. Harding" <tobin@kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
Roman Gushchin <guro@fb.com>,
Alexander Viro <viro@ftp.linux.org.uk>,
Christoph Hellwig <hch@infradead.org>,
Pekka Enberg <penberg@cs.helsinki.fi>,
David Rientjes <rientjes@google.com>,
Joonsoo Kim <iamjoonsoo.kim@lge.com>,
Matthew Wilcox <willy@infradead.org>,
Miklos Szeredi <mszeredi@redhat.com>,
Andreas Dilger <adilger@dilger.ca>,
Waiman Long <longman@redhat.com>,
Tycho Andersen <tycho@tycho.ws>, Theodore Ts'o <tytso@mit.edu>,
Andi Kleen <ak@linux.intel.com>,
David Chinner <david@fromorbit.com>,
Nick Piggin <npiggin@gmail.com>, Rik van Riel <riel@redhat.com>,
Hugh Dickins <hughd@google.com>,
linux-mm@kvack.org, linux-fsdevel@vger.kernel.org,
linux-kernel@vger.kernel.org,
Linus Torvalds <torvalds@linux-foundation.org>
Subject: Re: [RFC PATCH v2 14/14] dcache: Implement object migration
Date: Thu, 4 Apr 2019 15:46:31 +0000 [thread overview]
Message-ID: <01000169e907b8a0-2dbaab3f-18ad-4744-a81a-78809e2b7756-000000@email.amazonses.com> (raw)
In-Reply-To: <20190403182454.GU2217@ZenIV.linux.org.uk>
On Wed, 3 Apr 2019, Al Viro wrote:
> > This is an RFC and we want to know how to do this right.
>
> If by "how to do it right" you mean "expedit kicking out something with
> non-zero refcount" - there's no way to do that. Nothing even remotely
> sane.
Sure we know that.
> If you mean "kick out everything in this page with zero refcount" - that
> can be done (see further in the thread).
Ok that would already be progress. If we can use this to liberate some
slab pages with just a few dentry object then it may be worthwhile.
> Look, dentries and inodes are really, really not relocatable. If they
> can be evicted by memory pressure - sure, we can do that for a given
> set (e.g. "everything in that page"). But that's it - if memory
> pressure would _not_ get rid of that one, there's nothing to be done.
> Again, all VM can do is to simulate shrinker hitting hard on given
> bunch (rather than buggering the entire cache). If filesystem (or
> something in VFS) says "it's busy", it bloody well _is_ busy and
> won't be going away until it ceases to be such.
Right. Thats why the patch attempted to check for these things to avoid
touching such objects.
prev parent reply other threads:[~2019-04-04 15:46 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-04-03 4:21 [RFC PATCH v2 00/14] Slab Movable Objects (SMO) Tobin C. Harding
2019-04-03 4:21 ` [RFC PATCH v2 01/14] slub: Add isolate() and migrate() methods Tobin C. Harding
2019-04-03 4:21 ` [RFC PATCH v2 02/14] tools/vm/slabinfo: Add support for -C and -M options Tobin C. Harding
2019-04-03 4:21 ` [RFC PATCH v2 03/14] slub: Sort slab cache list Tobin C. Harding
2019-04-03 4:21 ` [RFC PATCH v2 04/14] slub: Slab defrag core Tobin C. Harding
2019-04-03 4:21 ` [RFC PATCH v2 05/14] tools/vm/slabinfo: Add remote node defrag ratio output Tobin C. Harding
2019-04-03 4:21 ` [RFC PATCH v2 06/14] tools/vm/slabinfo: Add defrag_used_ratio output Tobin C. Harding
2019-04-03 4:21 ` [RFC PATCH v2 07/14] tools/testing/slab: Add object migration test module Tobin C. Harding
2019-04-03 4:21 ` [RFC PATCH v2 08/14] tools/testing/slab: Add object migration test suite Tobin C. Harding
2019-04-03 4:21 ` [RFC PATCH v2 09/14] xarray: Implement migration function for objects Tobin C. Harding
2019-04-03 17:23 ` Matthew Wilcox
2019-04-03 21:19 ` Tobin C. Harding
2019-04-03 4:21 ` [RFC PATCH v2 10/14] tools/testing/slab: Add XArray movable objects tests Tobin C. Harding
2019-04-03 4:21 ` [RFC PATCH v2 11/14] slub: Enable moving objects to/from specific nodes Tobin C. Harding
2019-04-03 4:21 ` [RFC PATCH v2 12/14] slub: Enable balancing slabs across nodes Tobin C. Harding
2019-04-03 4:21 ` [RFC PATCH v2 13/14] dcache: Provide a dentry constructor Tobin C. Harding
2019-04-03 4:21 ` [RFC PATCH v2 14/14] dcache: Implement object migration Tobin C. Harding
2019-04-03 17:08 ` Al Viro
2019-04-03 17:19 ` Al Viro
2019-04-03 17:48 ` Al Viro
2019-04-04 20:29 ` Tobin C. Harding
2019-04-04 21:58 ` Al Viro
2019-04-04 21:18 ` Tobin C. Harding
2019-04-03 17:56 ` Christopher Lameter
2019-04-03 18:24 ` Al Viro
2019-04-03 19:05 ` Al Viro
2019-04-04 8:01 ` Miklos Szeredi
2019-04-04 15:46 ` Christopher Lameter [this message]
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