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, linux-kernel@vger.kernel.org
Cc: peterx@redhat.com, aarcange@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: [RFC PATCH V3 0/6] vhost: accelerate metadata access
Date: Tue, 23 Apr 2019 01:54:14 -0400 [thread overview]
Message-ID: <20190423055420.26408-1-jasowang@redhat.com> (raw)
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 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 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 | 852 ++++++++++++++++++++++++++++++++++++------
drivers/vhost/vhost.h | 34 +-
3 files changed, 764 insertions(+), 126 deletions(-)
--
2.18.1
next reply other threads:[~2019-04-23 5:54 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-04-23 5:54 Jason Wang [this message]
2019-04-23 5:54 ` [RFC PATCH V3 1/6] vhost: generalize adding used elem Jason Wang
2019-04-23 5:54 ` [RFC PATCH V3 2/6] vhost: fine grain userspace memory accessors Jason Wang
2019-04-23 5:54 ` [RFC PATCH V3 3/6] vhost: rename vq_iotlb_prefetch() to vq_meta_prefetch() Jason Wang
2019-04-23 5:54 ` [RFC PATCH V3 4/6] vhost: introduce helpers to get the size of metadata area Jason Wang
2019-04-23 5:54 ` [RFC PATCH V3 5/6] vhost: factor out setting vring addr and num Jason Wang
2019-04-23 5:54 ` [RFC PATCH V3 6/6] vhost: access vq metadata through kernel virtual address Jason Wang
2019-05-05 9:20 ` [RFC PATCH V3 0/6] vhost: accelerate metadata access Jason Wang
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