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Re: [Qemu-devel] [sneak preview] major scsi overhaul
From: |
Hannes Reinecke |
Subject: |
Re: [Qemu-devel] [sneak preview] major scsi overhaul |
Date: |
Thu, 26 Nov 2009 16:50:26 +0100 |
User-agent: |
Thunderbird 2.0.0.19 (X11/20081227) |
Gerd Hoffmann wrote:
> On 11/26/09 15:27, Hannes Reinecke wrote:
>> Gerd Hoffmann wrote:
>>> sd_done() tries to figure how many sectors it actually got for serious
>>> errors. I don't feel signaling "medium error" for the first sector
>>> behind our limit just because we'd like to have smaller requests.
>
>> scsi_end_request is being called with the number of bytes _actually
>> processed_,
>> which might be less than the number of bytes requested.
>> And the remainder will be retried by the upper layers.
>
> The "number of bytes _actually processed_" must come from somewhere. And
> that somewhere is sd_done() in case of scsi-disks. See my point now?
>
Ah. Now. I concur.
So indeed, this approach would only work if we signal some sense code
back to the host.
I, OTOH, don't have any qualms with returning HARDWARE_ERROR,
0x26/0x08(TOO MANY SEGMENT DESCRIPTORS) resp 0x26h/0x0B (INLINE DATA LENGTH
EXCEEDED).
Feels only fair to notify the guest it has done something wrong.
The alternative would be to split the I/O into smaller sections.
But this really feels a bit like an overkill.
Cheers,
Hannes
--
Dr. Hannes Reinecke zSeries & Storage
address@hidden +49 911 74053 688
SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 Nürnberg
GF: Markus Rex, HRB 16746 (AG Nürnberg)
- Re: [Qemu-devel] [sneak preview] major scsi overhaul, (continued)
- Re: [Qemu-devel] [sneak preview] major scsi overhaul, Paul Brook, 2009/11/24
- Re: [Qemu-devel] [sneak preview] major scsi overhaul, Gerd Hoffmann, 2009/11/25
- Re: [Qemu-devel] [sneak preview] major scsi overhaul, Hannes Reinecke, 2009/11/26
- Re: [Qemu-devel] [sneak preview] major scsi overhaul, Gerd Hoffmann, 2009/11/26
- Re: [Qemu-devel] [sneak preview] major scsi overhaul, Hannes Reinecke, 2009/11/26
- Re: [Qemu-devel] [sneak preview] major scsi overhaul, Gerd Hoffmann, 2009/11/26
- Re: [Qemu-devel] [sneak preview] major scsi overhaul, Hannes Reinecke, 2009/11/26
- Re: [Qemu-devel] [sneak preview] major scsi overhaul, Gerd Hoffmann, 2009/11/26
- Re: [Qemu-devel] [sneak preview] major scsi overhaul, Hannes Reinecke, 2009/11/26
- Re: [Qemu-devel] [sneak preview] major scsi overhaul, Gerd Hoffmann, 2009/11/26
- Re: [Qemu-devel] [sneak preview] major scsi overhaul,
Hannes Reinecke <=
- Re: [Qemu-devel] [sneak preview] major scsi overhaul, Gerd Hoffmann, 2009/11/27
- Re: [Qemu-devel] [sneak preview] major scsi overhaul, Ryan Harper, 2009/11/16
- Re: [Qemu-devel] [sneak preview] major scsi overhaul, Gerd Hoffmann, 2009/11/16
- Re: [Qemu-devel] [sneak preview] major scsi overhaul, Ryan Harper, 2009/11/16
[Qemu-devel] Re: [sneak preview] major scsi overhaul, Gerd Hoffmann, 2009/11/11