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xen-devel
Re: [Xen-devel] Re: Next steps with pv_ops for Xen
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To: |
Mark Williamson <mark.williamson@xxxxxxxxxxxx> |
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Subject: |
Re: [Xen-devel] Re: Next steps with pv_ops for Xen |
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From: |
tgh <wwwwww4187@xxxxxxxxxxx> |
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Date: |
Tue, 04 Dec 2007 17:35:44 +0800 |
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Cc: |
xen-devel@xxxxxxxxxxxxxxxxxxx, 'Eduardo Habkost' <ehabkost@xxxxxxxxxx>, 'Juan Quintela' <quintela@xxxxxxxxxx>, "'Stephen C. Tweedie'" <sct@xxxxxxxxxx>, 'Jan Beulich' <jbeulich@xxxxxxxxxx>, 'Glauber de Oliveira Costa' <gcosta@xxxxxxxxxx>, 'Chris Wright' <chrisw@xxxxxxxxxxxx>, virtualization@xxxxxxxxxxxxxx, dgm36@xxxxxxxxx, 'Gerd Hoffmann' <kraxel@xxxxxxxxxx> |
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Tue, 04 Dec 2007 01:36:25 -0800 |
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hi
I am not quite clear about the purpose of pv-ops , what do we want to
deal with by developping "pv-ops"? is it used for HVM or for PV or KVM
or something ? I have seen it for a few months in the list ,and
"pv-ops"is an active project ,but i am not clear about what is the aim
of "pv-ops" ,could you give me an explanation about it
Thanks in advance
Mark Williamson 写道:
Hi Mark,
Maybe a change to the gntdev userspace API to allow batching
of mapping requests?
Something along the lines of the following?
Just like that :-D
When you said "multiple syscalls per mapping" I assumed you meant that we'd
lose the batching you get by doing a mulicall. If it's just a couple of
syscalls (plus, presumably a couple of hypercalls) per batch of mappings, my
gut says it's probably not going to hurt block performance. My guts have
been wrong in (many!) ways before of course...
I guess the overhead *could* be reduced even more by just having a magic ioctl
that did all the mmap-ing stuff in one operation, but that'd probably be
really gross if it wasn't necessary! And I doubt it'd make upstream very
happy...
We'll also be eliminating the overheads involved in having a blktap ring for
talking to userspace and having to move requests between that ring and the
real block ring, so there's some definite wins in overheads as well.
Cheers,
Mark
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