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| From: | Peter Lieven |
| Subject: | Re: [Qemu-devel] [PATCH 2/4] block: immediately cancel oversized read/write requests |
| Date: | Mon, 08 Sep 2014 17:18:47 +0200 |
| User-agent: | Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.0 |
On 08.09.2014 17:15, Paolo Bonzini wrote:
Il 08/09/2014 17:13, ronnie sahlberg ha scritto:What I would like to see would also be to report these limitations to the guest itself to prevent it from generating too large I/Os.That's difficult because you don't want a backend change (e.g. from local storage to iSCSI) to change the vital product data in the guest.
I hadn't that in mind....
That's why we have splitting code for discard, and why we would have to add it for read/write too.
Why should a guest generate such big requests. Afaik the reported limit for e.g. virtio-blk is 1024 sectors (reported through blockdev --getmaxsect /dev/vda). I think it was only the multiwrite_merge code causing trouble here. Peter
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