| Message ID | 20121128215308.GA23360@redhat.com |
|---|---|
| State | New |
| Headers | show |
On (Wed) 28 Nov 2012 [23:53:08], Michael S. Tsirkin wrote: > On Tue, Nov 27, 2012 at 06:25:04PM +0200, Michael S. Tsirkin wrote: > > On Thu, Nov 01, 2012 at 06:07:21PM +0200, Michael S. Tsirkin wrote: > > > Commit 0d8d7690850eb0cf2b2b60933cf47669a6b6f18f introduced > > > a regression in virtio-net performance because it looks > > > into the ring aggressively while we really only care > > > about a single packet worth of buffers. > > > To fix, add parameters limiting lookahead, and > > > use in virtqueue_avail_bytes. > > > > > > Signed-off-by: Michael S. Tsirkin <mst@redhat.com> > > > Reported-by: Edivaldo de Araujo Pereira <edivaldoapereira@yahoo.com.br> > > > > Ping. > > Anthony - going to apply this? > > virtio rng was added since so naturally build broke. > Here's a patch on top to fix it up. I never used virtio rng before so > could not test at this hour, but it does fix the build. > > I'll take a look at how to test it tomorrow but any > info would be appreciated. > Amit could you pls review? Looks fine, I assume you will send a v2 of the patch to Anthony? Amit
On Thu, Nov 29, 2012 at 06:34:46PM +0530, Amit Shah wrote: > On (Wed) 28 Nov 2012 [23:53:08], Michael S. Tsirkin wrote: > > On Tue, Nov 27, 2012 at 06:25:04PM +0200, Michael S. Tsirkin wrote: > > > On Thu, Nov 01, 2012 at 06:07:21PM +0200, Michael S. Tsirkin wrote: > > > > Commit 0d8d7690850eb0cf2b2b60933cf47669a6b6f18f introduced > > > > a regression in virtio-net performance because it looks > > > > into the ring aggressively while we really only care > > > > about a single packet worth of buffers. > > > > To fix, add parameters limiting lookahead, and > > > > use in virtqueue_avail_bytes. > > > > > > > > Signed-off-by: Michael S. Tsirkin <mst@redhat.com> > > > > Reported-by: Edivaldo de Araujo Pereira <edivaldoapereira@yahoo.com.br> > > > > > > Ping. > > > Anthony - going to apply this? > > > > virtio rng was added since so naturally build broke. > > Here's a patch on top to fix it up. I never used virtio rng before so > > could not test at this hour, but it does fix the build. > > > > I'll take a look at how to test it tomorrow but any > > info would be appreciated. > > Amit could you pls review? > > Looks fine, I assume you will send a v2 of the patch to Anthony? > > Amit Anthony volunteered to test this so there will only be v2 if he sees problems.
"Michael S. Tsirkin" <mst@redhat.com> writes: > On Thu, Nov 29, 2012 at 06:34:46PM +0530, Amit Shah wrote: >> On (Wed) 28 Nov 2012 [23:53:08], Michael S. Tsirkin wrote: >> > On Tue, Nov 27, 2012 at 06:25:04PM +0200, Michael S. Tsirkin wrote: >> > > On Thu, Nov 01, 2012 at 06:07:21PM +0200, Michael S. Tsirkin wrote: >> > > > Commit 0d8d7690850eb0cf2b2b60933cf47669a6b6f18f introduced >> > > > a regression in virtio-net performance because it looks >> > > > into the ring aggressively while we really only care >> > > > about a single packet worth of buffers. >> > > > To fix, add parameters limiting lookahead, and >> > > > use in virtqueue_avail_bytes. >> > > > >> > > > Signed-off-by: Michael S. Tsirkin <mst@redhat.com> >> > > > Reported-by: Edivaldo de Araujo Pereira <edivaldoapereira@yahoo.com.br> >> > > >> > > Ping. >> > > Anthony - going to apply this? >> > >> > virtio rng was added since so naturally build broke. >> > Here's a patch on top to fix it up. I never used virtio rng before so >> > could not test at this hour, but it does fix the build. >> > >> > I'll take a look at how to test it tomorrow but any >> > info would be appreciated. >> > Amit could you pls review? >> >> Looks fine, I assume you will send a v2 of the patch to Anthony? >> >> Amit > > > Anthony volunteered to test this so there will only be v2 if he sees > problems. I need a Signed-off-by so why don't you just go ahead and send a v2 and I'll test that. Regards, Anthony Liguori
> I need a Signed-off-by so why don't you just go ahead and send a v2 and > I'll test that. OK I sent a v2 which is this fixup + the original patch smashed together.
diff --git a/hw/virtio-rng.c b/hw/virtio-rng.c index df329f2..a73ef8e 100644 --- a/hw/virtio-rng.c +++ b/hw/virtio-rng.c @@ -43,11 +43,11 @@ static bool is_guest_ready(VirtIORNG *vrng) return false; } -static size_t get_request_size(VirtQueue *vq) +static size_t get_request_size(VirtQueue *vq, unsigned quota) { unsigned int in, out; - virtqueue_get_avail_bytes(vq, &in, &out); + virtqueue_get_avail_bytes(vq, &in, &out, quota, 0); return in; } @@ -84,12 +84,18 @@ static void chr_read(void *opaque, const void *buf, size_t size) static void virtio_rng_process(VirtIORNG *vrng) { size_t size; + unsigned quota; if (!is_guest_ready(vrng)) { return; } - size = get_request_size(vrng->vq); + if (vrng->quota_remaining < 0) { + quota = 0; + } else { + quota = MIN((uint64_t)vrng->quota_remaining, (uint64_t)UINT32_MAX); + } + size = get_request_size(vrng->vq, quota); size = MIN(vrng->quota_remaining, size); if (size) { rng_backend_request_entropy(vrng->rng, size, chr_read, vrng);