From: Paolo Bonzini <pbonzini@redhat.com>
To: Asias He <asias@redhat.com>
Cc: kvm@vger.kernel.org, "Michael S. Tsirkin" <mst@redhat.com>,
virtualization@lists.linux-foundation.org,
target-devel@vger.kernel.org,
Stefan Hajnoczi <stefanha@redhat.com>
Subject: Re: [PATCH 3/4] tcm_vhost: Fix vs->vs_endpoint checking in vhost_scsi_handle_vq()
Date: Wed, 13 Mar 2013 09:02:38 +0100 [thread overview]
Message-ID: <5140329E.6090408@redhat.com> (raw)
In-Reply-To: <20130313031303.GD15369@hj.localdomain>
Il 13/03/2013 04:13, Asias He ha scritto:
>> > This takes dev mutex on data path which will introduce
>> > contention esp for multiqueue.
> Yes, for now it is okay, but for concurrent execution of multiqueue it is
> really bad.
>
> By the way, what is the overhead of taking and releasing the
> vs->dev.mutex even if no one contents for it? Is this overhead gnorable.
There is a possibility of cacheline ping-pong, but apart from that it's
ignorable.
>> > How about storing the endpoint as part of vq
>> > private data and protecting with vq mutex?
>
> Hmm, this makes sense, let's see how well it works.
Then VHOST_SCSI_SET_ENDPOINT would have to go through all vqs, no? A
rwlock seems simpler.
Paolo
next prev parent reply other threads:[~2013-03-13 8:02 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-03-12 2:42 [PATCH 0/4] tcm_vhost lock and flush fix Asias He
2013-03-12 2:42 ` [PATCH 1/4] tcm_vhost: Add missed lock in vhost_scsi_clear_endpoint() Asias He
2013-03-12 11:13 ` Michael S. Tsirkin
2013-03-13 2:54 ` Asias He
2013-03-13 2:54 ` Asias He
2013-03-12 2:42 ` [PATCH 2/4] tcm_vhost: Introduce tcm_vhost_check_endpoint() Asias He
2013-03-12 8:26 ` Paolo Bonzini
2013-03-13 3:02 ` Asias He
2013-03-13 8:00 ` Paolo Bonzini
2013-03-14 2:14 ` Asias He
2013-03-12 2:42 ` [PATCH 3/4] tcm_vhost: Fix vs->vs_endpoint checking in vhost_scsi_handle_vq() Asias He
2013-03-12 11:11 ` Michael S. Tsirkin
2013-03-13 3:13 ` Asias He
2013-03-13 8:02 ` Paolo Bonzini [this message]
2013-03-14 2:12 ` Asias He
2013-03-12 2:42 ` [PATCH 4/4] tcm_vhost: Flush vhost_work in vhost_scsi_flush() Asias He
2013-03-12 2:42 ` Asias He
2013-03-12 8:26 ` [PATCH 0/4] tcm_vhost lock and flush fix Paolo Bonzini
2013-03-12 11:12 ` Michael S. Tsirkin
2013-03-12 11:14 ` Paolo Bonzini
2013-03-14 2:17 ` Asias He
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