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Re: [Qemu-devel] [PATCH v4 00/10] main-loop: switch to g_poll(3) on POSI
From: |
Laurent Desnogues |
Subject: |
Re: [Qemu-devel] [PATCH v4 00/10] main-loop: switch to g_poll(3) on POSIX hosts |
Date: |
Fri, 22 Feb 2013 11:07:45 +0100 |
On Wed, Feb 20, 2013 at 11:28 AM, Stefan Hajnoczi <address@hidden> wrote:
> Amos Kong <address@hidden> reported that file descriptors numbered higher
> than 1024 could crash QEMU. This is due to the fixed size of the fd_set type
> used for select(2) event polling.
>
> This series converts the main-loop.c and aio-posix.c select(2) calls to
> g_poll(3). This eliminates the fd_set type and allows QEMU to scale to high
> numbers of file descriptors.
>
> The g_poll(3) interface is a portable version of the poll(2) system call. The
> difference to select(2) is that fine-grained events (G_IO_IN, G_IO_OUT,
> G_IO_HUP, G_IO_ERR, G_IO_PRI) can be monitored instead of just
> read/write/exception. Also, there is no limit to the file descriptor numbers
> that may be used, allowing applications to scale to many file descriptors.
> See
> the documentation for details:
>
> http://developer.gnome.org/glib/2.28/glib-The-Main-Event-Loop.html#g-poll
g_poll isn't available in older glib versions used by CentOS (2.12
on CentOS 5.6).
Thanks,
Laurent
> The QEMU main loop works as follows today:
>
> 1. Call out to slirp, iohandlers, and glib sources to fill rfds/wfds/xfds with
> the file descriptors to select(2).
> 2. Perform the select(2) call.
> 3. Call out to slirp, iohandlers, and glib sources to handle events polled in
> rfds/wfds/xfds.
>
> The plan of attack is as follows:
>
> 1. Replace select(2) with g_poll(3). Use glue that converts between
> rfds/wfds/xfds and GPollFD so that the unconverted QEMU components still
> work.
>
> 2. Convert slirp, iohandlers, and glib source fill/poll functions to use
> GPollFD directly instead of rfds/wfds/xfds.
>
> 3. Drop the glue since all components now natively use GPollFD.
>
> 4. Convert aio-posix.c to g_poll(3) by reusing GPollFD.
>
> I have tested that the series builds and is bisectable on Linux and Windows
> hosts. But I have not done extensive testing on other host platforms or with
> long-term guests to check for performance regressions.
>
> v4:
> * Assign revents instead of bitwise OR to make code clearer [Laszlo]
> * Invoke pollfds_poll() only when select(2) succeeds [Laszlo]
> * Fix gpollfds_to_select(select_ret || g_poll_ret) call [Laszlo]
>
> v3:
> * Convert slirp/slirp.c to tabs to spaces [Blue Swirl]
>
> v2:
> * Replace custom Poller type with GArray [aliguori]
>
> Stefan Hajnoczi (10):
> main-loop: fix select_ret uninitialized variable warning
> main-loop: switch to g_poll() on POSIX hosts
> main-loop: switch POSIX glib integration to GPollFD
> slirp: slirp/slirp.c coding style cleanup
> slirp: switch to GPollFD
> iohandler: switch to GPollFD
> main-loop: drop rfds/wfds/xfds for good
> aio: extract aio_dispatch() from aio_poll()
> aio: convert aio_poll() to g_poll(3)
> aio: support G_IO_HUP and G_IO_ERR
>
> aio-posix.c | 130 ++++-----
> async.c | 2 +
> include/block/aio.h | 3 +
> include/qemu/main-loop.h | 4 +-
> iohandler.c | 40 ++-
> main-loop.c | 158 ++++++-----
> slirp/libslirp.h | 6 +-
> slirp/main.h | 1 -
> slirp/slirp.c | 673
> +++++++++++++++++++++++++----------------------
> slirp/socket.c | 9 -
> slirp/socket.h | 2 +
> stubs/slirp.c | 6 +-
> 12 files changed, 547 insertions(+), 487 deletions(-)
>
> --
> 1.8.1.2
>
>
- Re: [Qemu-devel] [PATCH v4 00/10] main-loop: switch to g_poll(3) on POSIX hosts, (continued)
- Re: [Qemu-devel] [PATCH v4 00/10] main-loop: switch to g_poll(3) on POSIX hosts, Jan Kiszka, 2013/02/21
- Re: [Qemu-devel] [PATCH v4 00/10] main-loop: switch to g_poll(3) on POSIX hosts, Paolo Bonzini, 2013/02/21
- Re: [Qemu-devel] [PATCH v4 00/10] main-loop: switch to g_poll(3) on POSIX hosts, Anthony Liguori, 2013/02/21
- Re: [Qemu-devel] [PATCH v4 00/10] main-loop: switch to g_poll(3) on POSIX hosts, Paolo Bonzini, 2013/02/21
- Re: [Qemu-devel] [PATCH v4 00/10] main-loop: switch to g_poll(3) on POSIX hosts, Anthony Liguori, 2013/02/21
- Re: [Qemu-devel] [PATCH v4 00/10] main-loop: switch to g_poll(3) on POSIX hosts, Jan Kiszka, 2013/02/21
- Re: [Qemu-devel] [PATCH v4 00/10] main-loop: switch to g_poll(3) on POSIX hosts, Stefan Hajnoczi, 2013/02/22
- Re: [Qemu-devel] [PATCH v4 00/10] main-loop: switch to g_poll(3) on POSIX hosts, Jan Kiszka, 2013/02/22
Re: [Qemu-devel] [PATCH v4 00/10] main-loop: switch to g_poll(3) on POSIX hosts, Laszlo Ersek, 2013/02/21
Re: [Qemu-devel] [PATCH v4 00/10] main-loop: switch to g_poll(3) on POSIX hosts,
Laurent Desnogues <=
Re: [Qemu-devel] [PATCH v4 00/10] main-loop: switch to g_poll(3) on POSIX hosts, Anthony Liguori, 2013/02/22