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From: Jason Wang <jasowang@redhat.com>
To: mst@redhat.com, jasowang@redhat.com, kvm@vger.kernel.org,
	virtualization@lists.linux-foundation.org,
	netdev@vger.kernel.org
Cc: linux-kernel@vger.kernel.org, peterx@redhat.com,
	James.Bottomley@hansenpartnership.com, hch@infradead.org,
	davem@davemloft.net, jglisse@redhat.com, linux-mm@kvack.org,
	linux-arm-kernel@lists.infradead.org,
	linux-parisc@vger.kernel.org, christophe.de.dinechin@gmail.com,
	jrdr.linux@gmail.com
Subject: [PATCH net-next 0/6] vhost: accelerate metadata access
Date: Fri, 24 May 2019 04:12:12 -0400
Message-ID: <20190524081218.2502-1-jasowang@redhat.com> (raw)

Hi:

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 like SMAP. This is done through setup kernel address through
direct mapping and co-opreate VM management with MMU notifiers.

Test shows about 23% improvement on TX PPS. TCP_STREAM doesn't see
obvious improvement.

Thanks

Changes from RFC V3:
- rebase to net-next
- Tweak on the comments
Changes from RFC V2:
- switch to use direct mapping instead of vmap()
- switch to use spinlock + RCU to synchronize MMU notifier and vhost
  data/control path
- set dirty pages in the invalidation callbacks
- always use copy_to/from_users() friends for the archs that may need
  flush_dcache_pages()
- various minor fixes
Changes from V4:
- use invalidate_range() instead of invalidate_range_start()
- track dirty pages
Changes from V3:
- don't try to use vmap for file backed pages
- rebase to master
Changes from V2:
- fix buggy range overlapping check
- tear down MMU notifier during vhost ioctl to make sure
  invalidation request can read metadata userspace address and vq size
  without holding vq mutex.
Changes from V1:
- instead of pinning pages, use MMU notifier to invalidate vmaps
  and remap duing metadata prefetch
- fix build warning on MIPS

Jason Wang (6):
  vhost: generalize adding used elem
  vhost: fine grain userspace memory accessors
  vhost: rename vq_iotlb_prefetch() to vq_meta_prefetch()
  vhost: introduce helpers to get the size of metadata area
  vhost: factor out setting vring addr and num
  vhost: access vq metadata through kernel virtual address

 drivers/vhost/net.c   |   4 +-
 drivers/vhost/vhost.c | 850 ++++++++++++++++++++++++++++++++++++------
 drivers/vhost/vhost.h |  38 +-
 3 files changed, 766 insertions(+), 126 deletions(-)

-- 
2.18.1


             reply index

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-05-24  8:12 Jason Wang [this message]
2019-05-24  8:12 ` [PATCH net-next 1/6] vhost: generalize adding used elem Jason Wang
2019-05-24  8:12 ` [PATCH net-next 2/6] vhost: fine grain userspace memory accessors Jason Wang
2019-05-24  8:12 ` [PATCH net-next 3/6] vhost: rename vq_iotlb_prefetch() to vq_meta_prefetch() Jason Wang
2019-05-24  8:12 ` [PATCH net-next 4/6] vhost: introduce helpers to get the size of metadata area Jason Wang
2019-05-24  8:12 ` [PATCH net-next 5/6] vhost: factor out setting vring addr and num Jason Wang
2019-05-24  8:12 ` [PATCH net-next 6/6] vhost: access vq metadata through kernel virtual address Jason Wang
2019-05-30 18:07 ` [PATCH net-next 0/6] vhost: accelerate metadata access David Miller
2019-05-30 18:13   ` Michael S. Tsirkin
2019-05-30 18:55     ` David Miller
2019-06-05 20:27 ` Michael S. Tsirkin
2019-06-10  3:50   ` Jason Wang

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