From: "Tobin C. Harding" <me@tobin.cc>
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>,
Christopher Lameter <cl@linux.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>, Jonathan Corbet <corbet@lwn.net>,
linux-mm@kvack.org, linux-fsdevel@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [RFC PATCH v3 14/15] dcache: Implement partial shrink via Slab Movable Objects
Date: Thu, 11 Apr 2019 12:48:21 +1000 [thread overview]
Message-ID: <20190411024821.GB6941@eros.localdomain> (raw)
In-Reply-To: <20190411023322.GD2217@ZenIV.linux.org.uk>
On Thu, Apr 11, 2019 at 03:33:22AM +0100, Al Viro wrote:
> On Thu, Apr 11, 2019 at 11:34:40AM +1000, Tobin C. Harding wrote:
> > +/*
> > + * d_isolate() - Dentry isolation callback function.
> > + * @s: The dentry cache.
> > + * @v: Vector of pointers to the objects to isolate.
> > + * @nr: Number of objects in @v.
> > + *
> > + * The slab allocator is holding off frees. We can safely examine
> > + * the object without the danger of it vanishing from under us.
> > + */
> > +static void *d_isolate(struct kmem_cache *s, void **v, int nr)
> > +{
> > + struct dentry *dentry;
> > + int i;
> > +
> > + for (i = 0; i < nr; i++) {
> > + dentry = v[i];
> > + __dget(dentry);
> > + }
> > +
> > + return NULL; /* No need for private data */
> > +}
>
> Huh? This is compeletely wrong; what you need is collecting the ones
> with zero refcount (and not on shrink lists) into a private list.
> *NOT* bumping the refcounts at all. And do it in your isolate thing.
Oh, so putting entries on a shrink list is enough to pin them?
>
> > +static void d_partial_shrink(struct kmem_cache *s, void **v, int nr,
> > + int node, void *_unused)
> > +{
> > + struct dentry *dentry;
> > + LIST_HEAD(dispose);
> > + int i;
> > +
> > + for (i = 0; i < nr; i++) {
> > + dentry = v[i];
> > + spin_lock(&dentry->d_lock);
> > + dentry->d_lockref.count--;
> > +
> > + if (dentry->d_lockref.count > 0 ||
> > + dentry->d_flags & DCACHE_SHRINK_LIST) {
> > + spin_unlock(&dentry->d_lock);
> > + continue;
> > + }
> > +
> > + if (dentry->d_flags & DCACHE_LRU_LIST)
> > + d_lru_del(dentry);
> > +
> > + d_shrink_add(dentry, &dispose);
> > +
> > + spin_unlock(&dentry->d_lock);
> > + }
>
> Basically, that loop (sans jerking the refcount up and down) should
> get moved into d_isolate().
> > +
> > + if (!list_empty(&dispose))
> > + shrink_dentry_list(&dispose);
> > +}
>
> ... with this left in d_partial_shrink(). And you obviously need some way
> to pass the list from the former to the latter...
Easy enough, we have a void * return value from the isolate function
just for this purpose.
Thanks Al, hackety hack ...
Tobin
next prev parent reply other threads:[~2019-04-11 2:49 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-04-11 1:34 [RFC PATCH v3 00/15] Slab Movable Objects (SMO) Tobin C. Harding
2019-04-11 1:34 ` [RFC PATCH v3 01/15] slub: Add isolate() and migrate() methods Tobin C. Harding
2019-04-11 1:34 ` [RFC PATCH v3 02/15] tools/vm/slabinfo: Add support for -C and -M options Tobin C. Harding
2019-04-11 1:34 ` [RFC PATCH v3 03/15] slub: Sort slab cache list Tobin C. Harding
2019-04-11 1:34 ` [RFC PATCH v3 04/15] slub: Slab defrag core Tobin C. Harding
2019-04-11 1:34 ` [RFC PATCH v3 05/15] tools/vm/slabinfo: Add remote node defrag ratio output Tobin C. Harding
2019-04-11 1:34 ` [RFC PATCH v3 06/15] tools/vm/slabinfo: Add defrag_used_ratio output Tobin C. Harding
2019-04-11 1:34 ` [RFC PATCH v3 07/15] tools/testing/slab: Add object migration test module Tobin C. Harding
2019-04-11 1:34 ` [RFC PATCH v3 08/15] tools/testing/slab: Add object migration test suite Tobin C. Harding
2019-04-11 1:34 ` [RFC PATCH v3 09/15] xarray: Implement migration function for objects Tobin C. Harding
2019-04-11 1:34 ` [RFC PATCH v3 10/15] tools/testing/slab: Add XArray movable objects tests Tobin C. Harding
2019-04-11 1:34 ` [RFC PATCH v3 11/15] slub: Enable moving objects to/from specific nodes Tobin C. Harding
2019-04-11 1:34 ` [RFC PATCH v3 12/15] slub: Enable balancing slabs across nodes Tobin C. Harding
2019-04-11 1:34 ` [RFC PATCH v3 13/15] dcache: Provide a dentry constructor Tobin C. Harding
2019-04-11 1:34 ` [RFC PATCH v3 14/15] dcache: Implement partial shrink via Slab Movable Objects Tobin C. Harding
2019-04-11 2:33 ` Al Viro
2019-04-11 2:48 ` Tobin C. Harding [this message]
2019-04-11 4:47 ` Al Viro
2019-04-11 5:05 ` Tobin C. Harding
2019-04-11 20:01 ` Al Viro
2019-04-11 21:02 ` Al Viro
2019-06-29 4:08 ` Al Viro
2019-06-29 4:38 ` shrink_dentry_list() logics change (was Re: [RFC PATCH v3 14/15] dcache: Implement partial shrink via Slab Movable Objects) Al Viro
2019-06-29 19:06 ` Al Viro
2019-06-29 22:29 ` Al Viro
2019-06-29 22:34 ` Al Viro
2019-07-01 9:26 ` Tobin C. Harding
2019-04-11 1:34 ` [RFC PATCH v3 15/15] dcache: Add CONFIG_DCACHE_SMO Tobin C. Harding
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