From: Max Reitz <mreitz@redhat.com>
To: Paolo Bonzini <pbonzini@redhat.com>, qemu-devel@nongnu.org
Cc: qemu-block@nongnu.org, mlevitsk@redhat.com
Subject: Re: [PATCH 05/11] block: add max_hw_transfer to BlockLimits
Date: Fri, 25 Jun 2021 09:58:04 +0200 [thread overview]
Message-ID: <3cc81f9e-d96c-ba38-a9fd-720c645f42c9@redhat.com> (raw)
In-Reply-To: <20210624180423.1322165-6-pbonzini@redhat.com>
On 24.06.21 20:04, Paolo Bonzini wrote:
> For block host devices, I/O can happen through either the kernel file
> descriptor I/O system calls (preadv/pwritev, io_submit, io_uring)
> or the SCSI passthrough ioctl SG_IO.
>
> In the latter case, the size of each transfer can be limited by the
> HBA, while for file descriptor I/O the kernel is able to split and
> merge I/O in smaller pieces as needed. Applying the HBA limits to
> file descriptor I/O results in more system calls and suboptimal
> performance, so this patch splits the max_transfer limit in two:
> max_transfer remains valid and is used in general, while max_hw_transfer
> is limited to the maximum hardware size. max_hw_transfer can then be
> included by the scsi-generic driver in the block limits page, to ensure
> that the stricter hardware limit is used.
>
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> ---
> block/block-backend.c | 13 +++++++++++++
> block/file-posix.c | 2 +-
> block/io.c | 2 ++
> hw/scsi/scsi-generic.c | 2 +-
> include/block/block_int.h | 7 +++++++
> include/sysemu/block-backend.h | 1 +
> 6 files changed, 25 insertions(+), 2 deletions(-)
Reviewed-by: Max Reitz <mreitz@redhat.com>
next prev parent reply other threads:[~2021-06-25 7:58 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-24 18:04 [PATCH v5 00/11] block: file-posix queue Paolo Bonzini
2021-06-24 18:04 ` [PATCH 01/11] file-posix: fix max_iov for /dev/sg devices Paolo Bonzini
2021-06-24 18:04 ` [PATCH 02/11] scsi-generic: pass max_segments via max_iov field in BlockLimits Paolo Bonzini
2021-06-24 18:04 ` [PATCH 03/11] osdep: provide ROUND_DOWN macro Paolo Bonzini
2021-06-25 7:42 ` Max Reitz
2021-06-25 8:26 ` Philippe Mathieu-Daudé
2021-06-24 18:04 ` [PATCH 04/11] block-backend: align max_transfer to request alignment Paolo Bonzini
2021-06-25 7:52 ` Max Reitz
2021-06-24 18:04 ` [PATCH 05/11] block: add max_hw_transfer to BlockLimits Paolo Bonzini
2021-06-25 7:58 ` Max Reitz [this message]
2021-06-24 18:04 ` [PATCH 06/11] file-posix: try BLKSECTGET on block devices too, do not round to power of 2 Paolo Bonzini
2021-06-25 8:19 ` Max Reitz
2021-06-24 18:04 ` [PATCH 07/11] block: feature detection for host block support Paolo Bonzini
2021-06-25 8:20 ` Max Reitz
2021-06-24 18:04 ` [PATCH 08/11] block: check for sys/disk.h Paolo Bonzini
2021-06-24 18:04 ` [PATCH 09/11] block: try BSD disk size ioctls one after another Paolo Bonzini
2021-06-25 8:29 ` Max Reitz
2021-06-24 18:04 ` [PATCH 10/11] block: detect DKIOCGETBLOCKCOUNT/SIZE before use Paolo Bonzini
2021-06-25 8:30 ` Max Reitz
2021-06-24 18:04 ` [PATCH 11/11] file-posix: handle EINTR during ioctl Paolo Bonzini
2021-06-25 8:30 ` Philippe Mathieu-Daudé
2021-06-25 8:35 ` Max Reitz
2021-06-25 8:37 ` [PATCH v5 00/11] block: file-posix queue Max Reitz
2021-06-25 8:52 ` Paolo Bonzini
2021-06-25 9:28 ` Max Reitz
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=3cc81f9e-d96c-ba38-a9fd-720c645f42c9@redhat.com \
--to=mreitz@redhat.com \
--cc=mlevitsk@redhat.com \
--cc=pbonzini@redhat.com \
--cc=qemu-block@nongnu.org \
--cc=qemu-devel@nongnu.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.