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From: "Pierre Barre" <pierre@barre.sh>
To: v9fs@lists.linux.dev, linux-fsdevel@vger.kernel.org
Cc: ericvh@kernel.org, lucho@ionkov.net, asmadeus@codewreck.org,
	linux_oss@crudebyte.com
Subject: [RFC] net/9p: raise MAX_SOCK_BUF beyond 1 MiB for fd/tcp/unix transports?
Date: Tue, 14 Apr 2026 16:26:36 +0200	[thread overview]
Message-ID: <c2c75b03-e95d-49f4-be9a-2429fde4b5fe@app.fastmail.com> (raw)

Hi all,

MAX_SOCK_BUF in net/9p/trans_fd.c currently caps msize at 1 MiB for the fd/tcp/unix transports. The commit that introduced this ceiling (22bb3b79290e, "net/9p: increase tcp max msize to 1MB") noted that a further bump would need the allocator moved off contiguous slab chunks.

That prerequisite appears to be met now: p9_fcall_init() in net/9p/client.c uses kvmalloc() when the transport sets supports_vmalloc = true, which fd/tcp/unix all do. So the original slab fragmentation argument against raising the cap no longer applies to these transports.

Before I put together a patch, I wanted to check:

1. Are there other reasons that the 1 MiB cap should stay?
2. If a bump is welcome, is there a target value you'd prefer (e.g. 16 MiB, 32 MiB)?

Thanks,
Pierre

             reply	other threads:[~2026-04-14 14:26 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-04-14 14:26 Pierre Barre [this message]
2026-04-16  1:51 ` [RFC] net/9p: raise MAX_SOCK_BUF beyond 1 MiB for fd/tcp/unix transports? Dominique Martinet

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