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Re: [Qemu-devel] [PATCH 00/18] dataplane: remove RFifoLock (including al
From: |
Christian Borntraeger |
Subject: |
Re: [Qemu-devel] [PATCH 00/18] dataplane: remove RFifoLock (including almost all previously sent patches) |
Date: |
Mon, 17 Oct 2016 10:58:19 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.3.0 |
On 10/13/2016 07:34 PM, Paolo Bonzini wrote:
> This patch reorganizes aio_poll callers to establish new rules for
> dataplane locking. The idea is that I/O operations on a dataplane
> BDS (i.e. one where the AioContext is not the main one) do not call
> aio_poll anymore. Instead, they wait for the operation to end in the
> other I/O thread, at which point the other I/O thread calls bdrv_wakeup
> to wake up the main thread.
>
> With this change, only one thread runs aio_poll for an AioContext.
> While aio_context_acquire/release is still needed to protect the BDSes,
> it need not interrupt the other thread's event loop anymore, and therefore
> it does not need contention callbacks anymore. Thus the patch can remove
> RFifoLock. This fixes possible hangs in bdrv_drain_all, reproducible (for
> example) by unplugging a virtio-scsi-dataplane device while there is I/O
> going on for a virtio-blk-dataplane on the same I/O thread.
Have you seen improvements or deteriorations in performance with single disks
or multiple disks? Is there a branch?
- [Qemu-devel] [PATCH 17/18] qemu-thread: introduce QemuRecMutex, (continued)
- [Qemu-devel] [PATCH 17/18] qemu-thread: introduce QemuRecMutex, Paolo Bonzini, 2016/10/13
- [Qemu-devel] [PATCH 15/18] block: only call aio_poll on the current thread's AioContext, Paolo Bonzini, 2016/10/13
- [Qemu-devel] [PATCH 16/18] iothread: release AioContext around aio_poll, Paolo Bonzini, 2016/10/13
- [Qemu-devel] [PATCH 14/18] block: prepare bdrv_reopen_multiple to release AioContext, Paolo Bonzini, 2016/10/13
- [Qemu-devel] [PATCH 18/18] aio: convert from RFifoLock to QemuRecMutex, Paolo Bonzini, 2016/10/13
- Re: [Qemu-devel] [PATCH 00/18] dataplane: remove RFifoLock (including almost all previously sent patches),
Christian Borntraeger <=