From: Christoph Hellwig <hch@infradead.org>
To: Eric Biggers <ebiggers@kernel.org>
Cc: Christoph Hellwig <hch@infradead.org>,
linux-block@vger.kernel.org, linux-mm@kvack.org,
linux-kernel@vger.kernel.org, Jens Axboe <axboe@kernel.dk>,
Vlastimil Babka <vbabka@kernel.org>, Harry Yoo <harry@kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
Hao Li <hao.li@linux.dev>, Christoph Lameter <cl@gentwo.org>,
David Rientjes <rientjes@google.com>,
Roman Gushchin <roman.gushchin@linux.dev>
Subject: Re: [PATCH 2/3] mm: support fallible mempool_alloc_bulk()
Date: Wed, 12 Aug 2026 06:36:17 -0700 [thread overview]
Message-ID: <anx20bxfhD05jeuM@infradead.org> (raw)
In-Reply-To: <20260811210338.GB1905@sol>
On Tue, Aug 11, 2026 at 02:03:38PM -0700, Eric Biggers wrote:
> On Tue, Aug 11, 2026 at 01:13:37PM -0700, Christoph Hellwig wrote:
> > What is actually efficient is do skip the mempool entirely from the
> > original submission context and do a non-mempool GFP_NOIO allocation,
> > and only in the extremely unlikely case that this fails fall back to
> > the rescruer thread.
>
> It definitely is *not* more efficient to fall back to a kworker for a
> small task (removing elements from a mempool that has them available)
> that could just be done synchronously.
That is not the point. The point is that mempool_alloc_bulk frequently
fails to allocate all pages, and just filling that with a plain
alloc_pages is way faster than calling into the mempool code in any
form. The case where we actually need the mempool entries is extremely
rare.
next prev parent reply other threads:[~2026-08-12 13:36 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-08-06 22:10 [PATCH 0/3] Fix a deadlock in blk-crypto-fallback Eric Biggers
2026-08-06 22:10 ` [PATCH 1/3] mm: make mempool_alloc_from_pool() return bool Eric Biggers
2026-08-10 15:59 ` Christoph Hellwig
2026-08-06 22:10 ` [PATCH 2/3] mm: support fallible mempool_alloc_bulk() Eric Biggers
2026-08-10 16:00 ` Christoph Hellwig
2026-08-10 16:14 ` Eric Biggers
2026-08-10 17:21 ` Christoph Hellwig
2026-08-10 18:22 ` Eric Biggers
2026-08-11 20:13 ` Christoph Hellwig
2026-08-11 21:03 ` Eric Biggers
2026-08-12 13:36 ` Christoph Hellwig [this message]
2026-08-06 22:10 ` [PATCH 3/3] blk-crypto-fallback: Fix deadlock when encrypting large bio in dm layer Eric Biggers
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