From: Keith Busch <kbusch@kernel.org>
To: Apachez <apachez@gmail.com>
Cc: linux-nvme@lists.infradead.org
Subject: Re: Increase maxsize of io_queue_depth for nvme driver?
Date: Sun, 14 Sep 2025 08:31:45 -0600 [thread overview]
Message-ID: <aMbR0aWqFjklHzfR@kbusch-mbp> (raw)
In-Reply-To: <CALbmT6fF+1n+W1r+JNyr8+yY8Ub7PB6yYT2gpS12MBLbuHk9hQ@mail.gmail.com>
On Sun, Sep 14, 2025 at 02:45:35PM +0200, Apachez wrote:
> I would like to propose that NVME_PCI_MAX_QUEUE_SIZE should be
> increased from 4095 to 32767 to match the current NVMe specification
> regarding MQES and to give the sysop ability to fully utilize the
> performance of the hardware being used, or am I missing something
> here?
We use the upper bits of the command id to detect duplicate completions,
so we don't have enough bits to tag commands beyond 4095. As far as I
know, though, we haven't seen such breakage in a *long* time. It's more
of a sanity thing to know with high certainty that duplicate completions
are not occurring.
But I don't think you'll see any performance difference by increasing
the queue depth. Devices saturate the link at far lower already, so
going higher just increases completion latency.
next prev parent reply other threads:[~2025-09-14 14:31 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-09-14 12:45 Increase maxsize of io_queue_depth for nvme driver? Apachez
2025-09-14 14:31 ` Keith Busch [this message]
[not found] ` <5836da67-1fdd-43ac-a039-58705ba1f370@nvidia.com>
2025-09-19 8:13 ` Apachez
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