From: Paolo Bonzini <pbonzini@redhat.com>
To: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Christian Hoff <christian.hoff@de.ibm.com>,
linux-kernel@vger.kernel.org, linux-scsi@vger.kernel.org,
rusty@rustcorp.com.au, kvm@vger.kernel.org
Subject: Re: Pe: [PATCH v5 1/3] virtio-scsi: first version
Date: Tue, 07 Feb 2012 12:26:07 +0100 [thread overview]
Message-ID: <4F310A4F.6060602@redhat.com> (raw)
In-Reply-To: <20120207111041.GA6674@redhat.com>
On 02/07/2012 12:10 PM, Michael S. Tsirkin wrote:
>>> Also, lun[1] = sc->device->id means that only 255 SCSI target IDs will be
>>> > >supported. Think about bigger usage scenarios, such as FCP networks with
>>> > >several hundred HBAs in the net. If you want to have the target ID<->HBA
>>> > >mapping the same as on the guest as on the host, then 255 virtual target
>>> > >IDs could be a limit.
>> >
>> > I think you would hit other scalability limitations well before
>> > that. I plan to give each target its own MSI-X interrupt, but there
>> > is no infinite supplies of those either.
> virtio-pci generally lets guests share MSI-X vectors between queues,
> why not allow this here?
Yes, of course. However, with dozens of queues, many of them will share
the same vector and all of them will be examined when you get the
interrupt. Even if you find the right balance between sharing (because
you have to) and separating (because of scalability), I wouldn't be
surprised if more than 255 targets do not work too well.
Anyway multiqueue is not even in this patchset, so there's more work to
do before we can worry. :)
Paolo
next prev parent reply other threads:[~2012-02-07 11:26 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-02-06 9:51 Pe: [PATCH v5 1/3] virtio-scsi: first version Christian Hoff
2012-02-07 9:54 ` Paolo Bonzini
2012-02-07 11:10 ` Michael S. Tsirkin
2012-02-07 11:26 ` Paolo Bonzini [this message]
2012-02-07 11:56 ` Christian Borntraeger
2012-02-07 12:31 ` Paolo Bonzini
2012-02-07 13:18 ` Christian Borntraeger
2012-02-07 13:59 ` Christian Hoff
2012-02-07 14:28 ` Paolo Bonzini
2012-02-08 13:37 ` Christian Hoff
2012-02-09 9:25 ` Paolo Bonzini
2012-02-09 12:18 ` Christian Hoff
2012-02-12 20:16 ` James Bottomley
2012-02-12 23:41 ` Rusty Russell
2012-02-13 7:05 ` Christian Borntraeger
2012-02-13 7:57 ` Dor Laor
2012-02-13 12:40 ` Nicholas A. Bellinger
2012-02-13 12:54 ` Dor Laor
2012-02-13 13:00 ` Michael S. Tsirkin
2012-02-13 13:13 ` ronnie sahlberg
2012-02-13 13:17 ` Paolo Bonzini
2012-02-13 13:18 ` Michael S. Tsirkin
2012-02-13 15:12 ` Hannes Reinecke
2012-02-13 20:42 ` ronnie sahlberg
2012-02-13 20:53 ` ronnie sahlberg
2012-02-13 22:59 ` Michael S. Tsirkin
2012-02-13 23:30 ` ronnie sahlberg
2012-02-13 23:33 ` Michael S. Tsirkin
2012-02-14 0:49 ` ronnie sahlberg
2012-02-14 1:11 ` Michael S. Tsirkin
2012-02-14 9:57 ` Paolo Bonzini
2012-02-13 11:08 ` Bart Van Assche
2012-02-13 9:19 ` Paolo Bonzini
2012-02-14 0:07 ` Rusty Russell
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=4F310A4F.6060602@redhat.com \
--to=pbonzini@redhat.com \
--cc=christian.hoff@de.ibm.com \
--cc=kvm@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-scsi@vger.kernel.org \
--cc=mst@redhat.com \
--cc=rusty@rustcorp.com.au \
/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 a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).