Hi All,
Am a newbie (to kvm, linux kernel, git, etc.) so apologize in advance for
missing/inaccurate info.
I am experiencing inconsistent behavior of guest gettimeofday, described below.
I have seen prior reference to the problem, however, it was not clear whether
the issue was solved or not and wh
Dor Laor redhat.com> writes:
>
> On 06/25/2009 04:25 PM, Eran Rom wrote:
> > Behavior:
> > Running a code doing:
> > t1 = gettimeofday
> > t2 = gettimeofday
> > while t2-t1< 5 minutes {
> > sleep(1)
> > t2 = gettimeofday
> &g
Avi Kivity redhat.com> writes:
> 2.6.27 has kvmclock.
>
Thanks a lot!
Will try the kvmclock
Eran
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Eran Rom il.ibm.com> writes:
>
> Avi Kivity redhat.com> writes:
>
> > 2.6.27 has kvmclock.
> >
> Thanks a lot!
> Will try the kvmclock
> Eran
>
Still getting a misbehaving clock:
guest uses kvmclock with kernel 2.6.27
host kernel is 2.6.27 wit
Eran Rom il.ibm.com> writes:
>
> Eran Rom il.ibm.com> writes:
>
> Still getting a misbehaving clock:
> guest uses kvmclock with kernel 2.6.27
> host kernel is 2.6.27 with kvm-qemu-87 & kvm-kmod-87
>
> getting:
> ...
> now = 21280
Glauber Costa redhat.com> writes:
> > This was happening with kvmclock back then when it did not handle
> > cpu frequency changes. What are the details of the host hw?
> >
> > Glauber, any clues?
> maybe it is exactly that. 2.6.27 is a little bit old, and probably does not
> have the fixes.
>
W
Glauber Costa redhat.com> writes:
>
> > This was happening with kvmclock back then when it did not handle
> > cpu frequency changes. What are the details of the host hw?
> >
> > Glauber, any clues?
> maybe it is exactly that. 2.6.27 is a little bit old, and probably does not
> have the fixes.
>
Eran Rom il.ibm.com> writes:
> > When Host and Guest ran 2.6.27 with kvm-87 (both qemu-kvm and kvm-kmod), the
> > problem persisted. Thus, I am looking for a kernel fix that is not
> part of KVM,
> > any lead? Am confined to use 2.6.27
> Marcelo Tosatti wrote on 16
Christoph Hellwig lst.de> writes:
>
> File size set to 131072 KB
> Record Size 4 KB
> O_DIRECT feature enabled
> Command line used: iozone -s 128m -r 4k -I -f /dev/sdb
Apologies for multiple posts, might have a problem with my mail.
Can you please elaborate more on the con
Christoph Hellwig lst.de> writes:
>
>
> File size set to 131072 KB
> Record Size 4 KB
> O_DIRECT feature enabled
> Command line used: iozone -s 128m -r 4k -I -f /dev/sdb
is /dev/sdb a local disk, network drive attached via FC/IB, something else?
What is the command line
Christoph Hellwig lst.de> writes:
> Michael suggested to me a while ago to try MSI with virtio-blk and I
> played with this small patch:
> which gave about 5% speedups on 4k sized reads and writes, see the full
> iozone output I attached.
>
> File size set to 131072 KB
> Record Siz
> Another issue I noticed while looking at the results is large
> fluctuations in ide results. The standard deviation of
> the ide results is very large. A large portion of the results are
> around 30GB/sec and around 80GB/sec.
> Is there any meaningful explanation for this large variation? Is ther
The "Host<-->Guest" calls in virtio_blk (using the generic virtio kick/notify)
are as follows:
Guest->Host
---
do_virtlkb_request calls kick in the guest side causing handle_output to be
called on the host side.
Host->Guest
---
virtio_blk_rw_complete calls notify in the host side
> with vhost-blk:
>
>
> # time dd if=/dev/vda of=/dev/null bs=128k iflag=direct
> 64+0 records in
> 64+0 records out
> 8388608 bytes (84 GB) copied, 126.135 seconds, 665 MB/s
>
> # time dd of=/dev/vda if=/dev/zero bs=2M oflag=direct
>
Can you please check both read &
Christoph Hellwig infradead.org> writes:
> Ok. cache=writeback performance is something I haven't bothered looking
> at at all. For cache=none any streaming write or random workload with
> large enough record sizes got basically the same performance as native
> using kernel aio, and same for w
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