From: Rik van Riel <riel@surriel.com>
To: Usama Arif <usama.arif@linux.dev>,
Herbert Xu <herbert@gondor.apana.org.au>,
davem@davemloft.net, terrelln@fb.com, dsterba@suse.com,
hannes@cmpxchg.org, yosry@kernel.org, nphamcs@gmail.com,
chengming.zhou@linux.dev,
Andrew Morton <akpm@linux-foundation.org>,
linux-crypto@vger.kernel.org, linux-mm@kvack.org,
linux-kernel@vger.kernel.org, shakeel.butt@linux.dev,
kernel-team@meta.com
Subject: Re: [PATCH 1/2] crypto: zstd - use vmalloc() for stream workspaces
Date: Wed, 11 Nov 2026 10:43:21 -0500 [thread overview]
Message-ID: <5cf37868cde9f220b5b6b60871864d8679454ac0.camel@surriel.com> (raw)
In-Reply-To: <20261111153532.1036709-2-usama.arif@linux.dev>
On Wed, 2026-11-11 at 07:07 -0800, Usama Arif wrote:
> The zstd acomp streams retain their workspaces after the last
> transform
> has been freed. The first is allocated during transform
> initialization;
> additional per-CPU streams are allocated on demand. They are released
> when the algorithm is unregistered.
>
> In a 4 KiB-page x86-64 build, each stream requests 1,566,281 bytes.
> If kvmalloc() succeeds via kmalloc(), it occupies an order-9 block
> (2 MiB). vmalloc() needs 383 backing pages (1,532 KiB), 516 KiB fewer
> per stream. Across 384 populated streams, that is 193.5 MiB less
>
Woah. Nice catch
> Signed-off-by: Usama Arif <usama.arif@linux.dev>
>
Reviewed-by: Rik van Riel <riel@surriel.com>
--
All Rights Reversed.
next prev parent reply other threads:[~2026-11-11 15:43 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-11-11 15:07 [PATCH 0/2] crypto: use vmalloc() for large " Usama Arif
2026-11-11 15:07 ` [PATCH 1/2] crypto: zstd - use vmalloc() for " Usama Arif
2026-11-11 15:43 ` Rik van Riel [this message]
2026-11-11 15:07 ` [PATCH 2/2] crypto: deflate " Usama Arif
2026-11-11 15:44 ` Rik van Riel
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