From: Kevin Wolf <kwolf@redhat.com>
To: Stefan Hajnoczi <stefanha@redhat.com>
Cc: qemu-devel@nongnu.org, "Paolo Bonzini" <pbonzini@redhat.com>,
"John Snow" <jsnow@redhat.com>, "Fam Zheng" <fam@euphon.net>,
"Peter Xu" <peterx@redhat.com>,
"Philippe Mathieu-Daudé" <philmd@linaro.org>,
"Michael S. Tsirkin" <mst@redhat.com>,
qemu-block@nongnu.org, "David Hildenbrand" <david@redhat.com>,
pkrempa@redhat.com, "Hanna Reitz" <hreitz@redhat.com>
Subject: Re: [PATCH 04/12] scsi: introduce requests_lock
Date: Mon, 10 Mar 2025 14:37:37 +0100 [thread overview]
Message-ID: <Z87rIcwaBfAaxzLs@redhat.com> (raw)
In-Reply-To: <20250213180043.713434-5-stefanha@redhat.com>
Am 13.02.2025 um 19:00 hat Stefan Hajnoczi geschrieben:
> SCSIDevice keeps track of in-flight requests for device reset and Task
> Management Functions (TMFs). The request list requires protection so
> that multi-threaded SCSI emulation can be implemented in commits that
> follow.
>
> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Some of this feels quite heavy-handed, and I imagine that having to take
the lock in every request could cause considerable lock contention only
so that we can iterate all requests in a slow path.
This works for now, but maybe in the long run, we want to teach the
SCSI layer about (virt)queues, and have a separate request list per
queue (= AioContext)?
Kevin
next prev parent reply other threads:[~2025-03-10 13:38 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-02-13 18:00 [PATCH 00/12] virtio-scsi: add iothread-vq-mapping parameter Stefan Hajnoczi
2025-02-13 18:00 ` [PATCH 01/12] scsi-disk: drop unused SCSIDiskState->bh field Stefan Hajnoczi
2025-03-11 9:29 ` Philippe Mathieu-Daudé
2025-02-13 18:00 ` [PATCH 02/12] dma: use current AioContext for dma_blk_io() Stefan Hajnoczi
2025-02-13 18:00 ` [PATCH 03/12] scsi: track per-SCSIRequest AioContext Stefan Hajnoczi
2025-02-13 18:00 ` [PATCH 04/12] scsi: introduce requests_lock Stefan Hajnoczi
2025-03-10 13:37 ` Kevin Wolf [this message]
2025-03-11 9:11 ` Stefan Hajnoczi
2025-02-13 18:00 ` [PATCH 05/12] virtio-scsi: introduce event and ctrl virtqueue locks Stefan Hajnoczi
2025-02-13 18:00 ` [PATCH 06/12] virtio-scsi: protect events_dropped field Stefan Hajnoczi
2025-02-13 18:00 ` [PATCH 07/12] virtio-scsi: perform TMFs in appropriate AioContexts Stefan Hajnoczi
2025-02-13 18:00 ` [PATCH 08/12] virtio-blk: extract cleanup_iothread_vq_mapping() function Stefan Hajnoczi
2025-02-13 18:00 ` [PATCH 09/12] virtio-blk: tidy up iothread_vq_mapping functions Stefan Hajnoczi
2025-02-13 18:00 ` [PATCH 10/12] virtio: extract iothread-vq-mapping.h API Stefan Hajnoczi
2025-02-13 18:00 ` [PATCH 11/12] virtio-scsi: add iothread-vq-mapping parameter Stefan Hajnoczi
2025-03-10 14:33 ` Kevin Wolf
2025-03-10 14:37 ` Peter Krempa
2025-03-10 15:17 ` Kevin Wolf
2025-02-13 18:00 ` [PATCH 12/12] virtio-scsi: handle ctrl virtqueue in main loop Stefan Hajnoczi
2025-03-10 14:43 ` Kevin Wolf
2025-02-20 17:04 ` [PATCH 00/12] virtio-scsi: add iothread-vq-mapping parameter Peter Krempa
2025-03-10 14:43 ` Kevin Wolf
2025-03-11 9:22 ` Stefan Hajnoczi
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