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Re: [Qemu-devel] [RFC 08/13] block: drop bdrv_get_aio_context()
From: |
Paolo Bonzini |
Subject: |
Re: [Qemu-devel] [RFC 08/13] block: drop bdrv_get_aio_context() |
Date: |
Fri, 14 Jun 2013 10:12:00 -0400 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130514 Thunderbird/17.0.6 |
Il 14/06/2013 05:48, Stefan Hajnoczi ha scritto:
> Associating a BlockDriverState with a single AioContext is not flexible
> enough. Once we make BlockDriverState thread-safe, it will be possible
> to call bdrv_*() functions from multiple event loops.
I'm afraid that this is trading some pain now (converting
qemu_bh_new/qemu_set_fd_handler to aio_bh_new/aio_set_fd_handler) for
more pain later (having to make BDS thread-safe). There aren't that
many (~40) in block layer code.
Making BlockDriverState thread-safe is hard, it is much simpler to run
all the BlockDriverState code in the AioContext thread itself.
There are some things that cannot (basically monitor commands and other
places that are currently using bdrv_drain_all) but they can simply take
a "big AioContext lock".
Paolo
- [Qemu-devel] [RFC 01/13] block: fix bdrv_flush() ordering in bdrv_close(), (continued)
- [Qemu-devel] [RFC 01/13] block: fix bdrv_flush() ordering in bdrv_close(), Stefan Hajnoczi, 2013/06/14
- [Qemu-devel] [RFC 02/13] dataplane: sync virtio.c and vring.c virtqueue state, Stefan Hajnoczi, 2013/06/14
- [Qemu-devel] [RFC 03/13] block: add BlockDevOps->drain_threads_cb(), Stefan Hajnoczi, 2013/06/14
- [Qemu-devel] [RFC 04/13] virtio-blk: implement BlockDevOps->drain_threads_cb(), Stefan Hajnoczi, 2013/06/14
- [Qemu-devel] [RFC 06/13] qemu-thread: add TLS wrappers, Stefan Hajnoczi, 2013/06/14
- [Qemu-devel] [RFC 07/13] block: add thread_aio_context TLS variable, Stefan Hajnoczi, 2013/06/14
- [Qemu-devel] [RFC 09/13] main-loop: use thread-local AioContext, Stefan Hajnoczi, 2013/06/14
- [Qemu-devel] [RFC 10/13] block: disable I/O throttling outside main loop, Stefan Hajnoczi, 2013/06/14
- [Qemu-devel] [RFC 08/13] block: drop bdrv_get_aio_context(), Stefan Hajnoczi, 2013/06/14
- Re: [Qemu-devel] [RFC 08/13] block: drop bdrv_get_aio_context(),
Paolo Bonzini <=
[Qemu-devel] [RFC 12/13] dataplane: drop ioq Linux AIO request queue, Stefan Hajnoczi, 2013/06/14
[Qemu-devel] [RFC 11/13] dataplane: use block layer for I/O, Stefan Hajnoczi, 2013/06/14
[Qemu-devel] [RFC 13/13] block: drop raw_get_aio_fd(), Stefan Hajnoczi, 2013/06/14
[Qemu-devel] [RFC 05/13] exec: do not use qemu/tls.h, Stefan Hajnoczi, 2013/06/14