From: Jason Wang <jasowang@redhat.com>
To: "Michael S. Tsirkin" <mst@redhat.com>
Cc: virtualization@lists.linux-foundation.org,
netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
kvm@vger.kernel.org
Subject: Re: [PATCH net-next V4 5/5] vhost: access vq metadata through kernel virtual address
Date: Fri, 25 Jan 2019 17:16:32 +0800 [thread overview]
Message-ID: <18e64692-2598-6e95-3b93-c34528d04c1b@redhat.com> (raw)
In-Reply-To: <20190124215912-mutt-send-email-mst@kernel.org>
On 2019/1/25 上午11:00, Michael S. Tsirkin wrote:
> On Thu, Jan 24, 2019 at 12:07:54PM +0800, Jason Wang wrote:
>>> Meanwhile, could you pls post data comparing this last patch with the
>>> below? This removes the speculation barrier replacing it with a
>>> (useless but at least more lightweight) data dependency.
>> SMAP off
>>
>> Your patch: 7.2MPPs
>>
>> vmap: 7.4Mpps
> OK so while we keep looking into vmap, why don't we merge something like
> the below? Seems quite straight forward ...
>
The problem is it gives ~8% regression on PPS when SMAP is on. This is
probably because the latency of lfence is hided by previous stac as
mentioned in the commit b3bbfb3fb5d25776b8e3f361d2eedaabb0b496cd.
Thanks
next prev parent reply other threads:[~2019-01-25 9:16 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-01-23 9:55 [PATCH net-next V4 0/5] vhost: accelerate metadata access through vmap() Jason Wang
2019-01-23 9:55 ` [PATCH net-next V4 1/5] vhost: generalize adding used elem Jason Wang
2019-01-23 9:55 ` [PATCH net-next V4 2/5] vhost: fine grain userspace memory accessors Jason Wang
2019-01-23 9:55 ` [PATCH net-next V4 3/5] vhost: rename vq_iotlb_prefetch() to vq_meta_prefetch() Jason Wang
2019-01-23 9:55 ` [PATCH net-next V4 4/5] vhost: introduce helpers to get the size of metadata area Jason Wang
2019-01-23 9:55 ` [PATCH net-next V4 5/5] vhost: access vq metadata through kernel virtual address Jason Wang
2019-01-23 14:08 ` Michael S. Tsirkin
2019-01-24 4:07 ` Jason Wang
2019-01-24 4:11 ` Jason Wang
2019-01-24 4:53 ` Michael S. Tsirkin
2019-01-25 2:33 ` Jason Wang
2019-01-24 4:51 ` Michael S. Tsirkin
2019-01-25 3:00 ` Michael S. Tsirkin
2019-01-25 9:16 ` Jason Wang [this message]
2019-01-25 3:03 ` Michael S. Tsirkin
2019-01-25 9:21 ` Jason Wang
2019-01-25 9:24 ` Jason Wang
2019-01-23 13:58 ` [PATCH net-next V4 0/5] vhost: accelerate metadata access through vmap() Michael S. Tsirkin
2019-01-23 17:24 ` David Miller
2019-01-26 22:37 ` David Miller
2019-01-27 0:31 ` Michael S. Tsirkin
2019-01-29 2:34 ` Jason Wang
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