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Re: [Qemu-devel] [Qemu-block] [PATCH v3 00/13] main-loop: Get rid of fd_
From: |
Stefan Hajnoczi |
Subject: |
Re: [Qemu-devel] [Qemu-block] [PATCH v3 00/13] main-loop: Get rid of fd_read_poll and qemu_set_fd_handler2 |
Date: |
Tue, 19 May 2015 16:02:38 +0100 |
User-agent: |
Mutt/1.5.23 (2014-03-12) |
On Tue, May 19, 2015 at 10:50:57AM +0000, Fam Zheng wrote:
> v3: Replace previous 13 with a simple return type conversion patch.
> Drop RFC.
>
> This carries out the mandate in the comment of qemu_set_fd_handler2 and
> removes
> fd_read_poll from the code base, because it will make the work easier to
> convert ppoll to epoll in main loop. Also, the aio interface doesn't have a
> read poll callback, which means this conversion woule be necessary if we want
> to move iohandler fds from main loop to AioContext.
>
> There are five users of the read poll callback now: qemu-nbd, l2tpv3, netmap,
> socket and tap, which are all covered.
>
> Patch 1 adds a stub for qemu_set_fd_handler which will be referenced in coming
> patches.
>
> Patch 2 converts qemu-nbd which compares two global numbers in the
> fd_read_poll
> callback.
>
> Patches 3~6 converts the four net devices, all of which checks
> qemu_can_send_packet() in the callback.
>
> Patch 7 and 8 finally removes the function.
>
> The rest patches are cleanup for the unuseful return value of
> qemu_set_fd_handler.
>
> Please review!
I looked at the first few patches.
The qemu-nbd.c conversion is good. It finds locations where read_poll
state transitions happen and updates file descriptor monitoring there.
The l2tpv3 and netmap conversion throws away read_poll and introduces
problems instead.
Please look at the patches again and either:
1. Convert everything like you converted qemu-nbd.c. This is a
conservative approach and we can be confident that behavior is
unchanged.
2. Convert more carefully, making sure that packets are actually
dropped and QEMU does not spin on a readable fd.
I prefer #1 because it's easier to check that behavior is still correct.
It also minimizes queuing inside QEMU.
Stefan
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- [Qemu-devel] [PATCH v3 01/13] stubs: Add qemu_set_fd_handler, (continued)
- [Qemu-devel] [PATCH v3 01/13] stubs: Add qemu_set_fd_handler, Fam Zheng, 2015/05/18
- [Qemu-devel] [PATCH v3 05/13] net/socket: Drop net_socket_can_send, Fam Zheng, 2015/05/18
- [Qemu-devel] [PATCH v3 09/13] alsaaudio: Remove unused error handling of qemu_set_fd_handler, Fam Zheng, 2015/05/18
- [Qemu-devel] [PATCH v3 10/13] oss: Remove unused error handling of qemu_set_fd_handler, Fam Zheng, 2015/05/18
- [Qemu-devel] [PATCH v3 06/13] tap: Drop tap_can_send, Fam Zheng, 2015/05/18
- [Qemu-devel] [PATCH v3 11/13] xen_backend: Remove unused error handling of qemu_set_fd_handler, Fam Zheng, 2015/05/18
- [Qemu-devel] [PATCH v3 12/13] event-notifier: Always return 0 for posix implementation, Fam Zheng, 2015/05/18
- [Qemu-devel] [PATCH v3 13/13] iohandler: Change return type of qemu_set_fd_handler to "void", Fam Zheng, 2015/05/18
- [Qemu-devel] [PATCH v3 08/13] main-loop: Drop qemu_set_fd_handler2, Fam Zheng, 2015/05/18
- [Qemu-devel] [PATCH v3 07/13] Change qemu_set_fd_handler2(..., NULL, ...) to qemu_set_fd_handler, Fam Zheng, 2015/05/18
- Re: [Qemu-devel] [Qemu-block] [PATCH v3 00/13] main-loop: Get rid of fd_read_poll and qemu_set_fd_handler2,
Stefan Hajnoczi <=