Re: [RFC PATCH V3 0/5] Hi: - Michael S. Tsirkin

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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  3:28 UTC|newest]

Thread overview: 59+ 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  7:00       ` Jason Wang
2019-01-07 14:50         ` Michael S. Tsirkin
2019-01-07 14:50         ` Michael S. Tsirkin
2019-01-04 21:29   ` Michael S. Tsirkin
2018-12-29 12:46 ` Jason Wang
2018-12-29 12:46 ` [RFC PATCH V3 2/5] vhost: fine grain userspace memory accessors Jason Wang
2018-12-29 12:46 ` 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 ` 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 ` Jason Wang
2018-12-29 12:46 ` [RFC PATCH V3 5/5] vhost: access vq metadata through kernel virtual address Jason Wang
2018-12-29 12:46 ` Jason Wang
2019-01-04 21:34   ` Michael S. Tsirkin
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
2019-01-02 20:47 ` Michael S. Tsirkin
2019-01-07  2:19   ` Jason Wang
2019-01-07  3:28     ` Michael S. Tsirkin
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
2019-01-07 14:37             ` Michael S. Tsirkin
2019-01-08 10:01               ` Jason Wang
2019-01-07  6:50           ` Jason Wang
2019-01-07  7:15           ` Dan Williams
2019-01-07 14:11             ` Michael S. Tsirkin
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
2019-01-09  5:19                       ` Linus Torvalds
2019-01-07 22:44                   ` [RFC PATCH V3 0/5] Hi: Dan Williams
2019-01-07 21:39               ` Dan Williams
2019-01-08 11:42               ` Jason Wang
2019-01-08 11:42               ` Jason Wang
2019-01-07  7:15           ` Dan Williams
2019-01-07  4:17         ` Michael S. Tsirkin
2019-01-07  2:19   ` 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
2019-01-07 14:47     ` Michael S. Tsirkin
2019-01-08 10:12       ` Jason Wang
2019-01-08 10:12       ` Jason Wang
2019-01-11  8:59         ` Jason Wang
2019-01-11  8:59         ` Jason Wang
2019-01-04 21:41 ` Michael S. Tsirkin
  -- strict thread matches above, loose matches on Subject: below --
2018-12-29 12:46 Jason Wang

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