From: "Michael S. Tsirkin" <mst@redhat.com>
To: Jason Wang <jasowang@redhat.com>
Cc: kvm@vger.kernel.org, virtualization@lists.linux-foundation.org,
netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
davem@davemloft.net
Subject: Re: [RFC PATCH V3 0/5] Hi:
Date: Sun, 6 Jan 2019 22:28:56 -0500 [thread overview]
Message-ID: <20190106221832-mutt-send-email-mst@kernel.org> (raw)
In-Reply-To: <0efd115a-a7fb-54bf-5376-59d047a15fd3@redhat.com>
On Mon, Jan 07, 2019 at 10:19:03AM +0800, Jason Wang wrote:
>
> On 2019/1/3 上午4:47, Michael S. Tsirkin wrote:
> > On Sat, Dec 29, 2018 at 08:46:51PM +0800, Jason Wang wrote:
> > > This series tries to access virtqueue metadata through kernel virtual
> > > address instead of copy_user() friends since they had too much
> > > overheads like checks, spec barriers or even hardware feature
> > > toggling.
> > Will review, thanks!
> > One questions that comes to mind is whether it's all about bypassing
> > stac/clac. Could you please include a performance comparison with
> > nosmap?
> >
>
> On machine without SMAP (Sandy Bridge):
>
> Before: 4.8Mpps
>
> After: 5.2Mpps
OK so would you say it's really unsafe versus safe accesses?
Or would you say it's just a better written code?
> On machine with SMAP (Broadwell):
>
> Before: 5.0Mpps
>
> After: 6.1Mpps
>
> No smap: 7.5Mpps
>
>
> Thanks
no smap being before or after?
--
MST
next prev parent reply other threads:[~2019-01-07 3:29 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-12-29 12:46 [RFC PATCH V3 0/5] Hi: Jason Wang
2018-12-29 12:46 ` [RFC PATCH V3 1/5] vhost: generalize adding used elem Jason Wang
2019-01-04 21:29 ` Michael S. Tsirkin
2019-01-05 0:33 ` Sean Christopherson
2019-01-07 7:00 ` Jason Wang
2019-01-07 14:50 ` Michael S. Tsirkin
2018-12-29 12:46 ` [RFC PATCH V3 2/5] vhost: fine grain userspace memory accessors Jason Wang
2018-12-29 12:46 ` [RFC PATCH V3 3/5] vhost: rename vq_iotlb_prefetch() to vq_meta_prefetch() Jason Wang
2018-12-29 12:46 ` [RFC PATCH V3 4/5] vhost: introduce helpers to get the size of metadata area Jason Wang
2018-12-29 12:46 ` [RFC PATCH V3 5/5] vhost: access vq metadata through kernel virtual address Jason Wang
2019-01-04 21:34 ` Michael S. Tsirkin
2019-01-07 8:40 ` Jason Wang
2019-01-02 20:47 ` [RFC PATCH V3 0/5] Hi: Michael S. Tsirkin
2019-01-07 2:19 ` Jason Wang
2019-01-07 3:28 ` Michael S. Tsirkin [this message]
2019-01-07 3:53 ` Jason Wang
2019-01-07 4:17 ` Michael S. Tsirkin
2019-01-07 6:50 ` Jason Wang
2019-01-07 14:37 ` Michael S. Tsirkin
2019-01-08 10:01 ` Jason Wang
2019-01-07 7:15 ` Dan Williams
2019-01-07 14:11 ` Michael S. Tsirkin
2019-01-07 21:39 ` Dan Williams
2019-01-07 22:25 ` Michael S. Tsirkin
2019-01-07 22:44 ` Dan Williams
2019-01-09 4:31 ` __get_user slower than get_user (was Re: [RFC PATCH V3 0/5] Hi:) Michael S. Tsirkin
2019-01-09 5:19 ` Linus Torvalds
2019-01-08 11:42 ` [RFC PATCH V3 0/5] Hi: Jason Wang
2019-01-04 21:41 ` Michael S. Tsirkin
2019-01-07 6:58 ` Jason Wang
2019-01-07 14:47 ` Michael S. Tsirkin
2019-01-08 10:12 ` Jason Wang
2019-01-11 8:59 ` Jason Wang
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