From: David Miller <davem@davemloft.net>
To: mst@redhat.com
Cc: jasowang@redhat.com, hch@infradead.org, kvm@vger.kernel.org,
virtualization@lists.linux-foundation.org,
netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
peterx@redhat.com, linux-mm@kvack.org, aarcange@redhat.com,
linux-arm-kernel@lists.infradead.org,
linux-parisc@vger.kernel.org
Subject: Re: [RFC PATCH V2 0/5] vhost: accelerate metadata access through vmap()
Date: Mon, 11 Mar 2019 11:14:13 -0700 (PDT) [thread overview]
Message-ID: <20190311.111413.1140896328197448401.davem@davemloft.net> (raw)
In-Reply-To: <20190311095405-mutt-send-email-mst@kernel.org>
From: "Michael S. Tsirkin" <mst@redhat.com>
Date: Mon, 11 Mar 2019 09:59:28 -0400
> On Mon, Mar 11, 2019 at 03:13:17PM +0800, Jason Wang wrote:
>>
>> On 2019/3/8 下午10:12, Christoph Hellwig wrote:
>> > On Wed, Mar 06, 2019 at 02:18:07AM -0500, 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. This is done through setup kernel address through vmap() and
>> > > resigter MMU notifier for invalidation.
>> > >
>> > > Test shows about 24% improvement on TX PPS. TCP_STREAM doesn't see
>> > > obvious improvement.
>> > How is this going to work for CPUs with virtually tagged caches?
>>
>>
>> Anything different that you worry?
>
> If caches have virtual tags then kernel and userspace view of memory
> might not be automatically in sync if they access memory
> through different virtual addresses. You need to do things like
> flush_cache_page, probably multiple times.
"flush_dcache_page()"
next prev parent reply other threads:[~2019-03-11 18:14 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <1551856692-3384-1-git-send-email-jasowang@redhat.com>
2019-03-08 14:12 ` [RFC PATCH V2 0/5] vhost: accelerate metadata access through vmap() Christoph Hellwig
2019-03-11 7:13 ` Jason Wang
2019-03-11 13:59 ` Michael S. Tsirkin
2019-03-11 18:14 ` David Miller [this message]
2019-03-12 2:59 ` Jason Wang
2019-03-12 3:52 ` Michael S. Tsirkin
2019-03-12 7:17 ` Jason Wang
2019-03-12 11:54 ` Michael S. Tsirkin
2019-03-12 15:46 ` James Bottomley
2019-03-12 20:04 ` Andrea Arcangeli
2019-03-12 20:53 ` James Bottomley
2019-03-12 21:11 ` Andrea Arcangeli
2019-03-12 21:19 ` James Bottomley
2019-03-12 21:53 ` Andrea Arcangeli
2019-03-12 22:02 ` James Bottomley
2019-03-12 22:50 ` Andrea Arcangeli
2019-03-12 22:57 ` James Bottomley
2019-03-13 16:05 ` Christoph Hellwig
2019-03-13 16:37 ` James Bottomley
2019-03-14 10:42 ` Michael S. Tsirkin
2019-03-14 13:49 ` Jason Wang
2019-03-14 19:33 ` Andrea Arcangeli
2019-03-15 4:39 ` Jason Wang
2019-03-12 5:14 ` James Bottomley
2019-03-12 7:51 ` Jason Wang
2019-03-12 7:53 ` Jason Wang
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