From: Christoph Hellwig <hch@lst.de>
To: Leon Romanovsky <leon@kernel.org>
Cc: Keith Busch <kbusch@kernel.org>, Christoph Hellwig <hch@lst.de>,
Keith Busch <kbusch@meta.com>,
linux-nvme@lists.infradead.org
Subject: Re: [PATCH] nvme-pci: always use blk_map_iter for metadata
Date: Mon, 27 Oct 2025 08:13:53 +0100 [thread overview]
Message-ID: <20251027071353.GA13854@lst.de> (raw)
In-Reply-To: <20251026072551.GB12554@unreal>
On Sun, Oct 26, 2025 at 09:25:51AM +0200, Leon Romanovsky wrote:
> > Maybe the data path should only use blk_dma_iter too. Is dma_map_bvec
> > that much faster for the single vector case? I'm going to test both on
> > real hardware and see if there's a difference in CPU utilization or
> > latency.
>
> We tried that path (remove special case for single segment), but for
> very performance oriented case: direct mode without IOMMU, no p2p and
> extremely powerful RAID (~94M IOPS), Jens and Kanchan saw performance
> drop. On consumer grade HW (~2M IOPS), the performance change was not
> noticed.
Yes. Sorry, I wanted to reply something like this to Keith earlier but
managed to drop the ball.
next prev parent reply other threads:[~2025-10-27 7:14 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-10-20 18:24 [PATCH] nvme-pci: always use blk_map_iter for metadata Keith Busch
2025-10-20 23:38 ` Chaitanya Kulkarni
2025-10-21 7:19 ` Christoph Hellwig
2025-10-21 14:42 ` Keith Busch
2025-10-26 7:25 ` Leon Romanovsky
2025-10-27 7:13 ` Christoph Hellwig [this message]
2025-10-27 16:09 ` Keith Busch
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20251027071353.GA13854@lst.de \
--to=hch@lst.de \
--cc=kbusch@kernel.org \
--cc=kbusch@meta.com \
--cc=leon@kernel.org \
--cc=linux-nvme@lists.infradead.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.