Re: [Qemu-devel] [PATCH v5] glib: fix g_poll early timeout on windows

[Stefan Weil]

Am 09.05.2014 20:57, schrieb Stefan Hajnoczi:
> On Thu, May 08, 2014 at 12:47:10PM +0400, Stanislav Vorobiov wrote:
>> From: Sangho Park <address@hidden>
>>
>> g_poll has a problem on Windows when using
>> timeouts < 10ms, in glib/gpoll.c:
>>
>> /* If not, and we have a significant timeout, poll again with
>>  * timeout then. Note that this will return indication for only
>>  * one event, or only for messages. We ignore timeouts less than
>>  * ten milliseconds as they are mostly pointless on Windows, the
>>  * MsgWaitForMultipleObjectsEx() call will timeout right away
>>  * anyway.
>>  */
>> if (retval == 0 && (timeout == INFINITE || timeout >= 10))
>>   retval = poll_rest (poll_msgs, handles, nhandles, fds, nfds, timeout);
>>
>> so whenever g_poll is called with timeout < 10ms it does
>> a quick poll instead of wait, this causes significant performance
>> degradation of QEMU, thus we should use WaitForMultipleObjectsEx
>> directly
>>
>> Signed-off-by: Stanislav Vorobiov <address@hidden>
>> ---
>>  include/glib-compat.h |    9 +++-
>>  util/oslib-win32.c    |  112 
>> +++++++++++++++++++++++++++++++++++++++++++++++++
>>  2 files changed, 120 insertions(+), 1 deletion(-)
> 
> Thanks, applied to my block tree:
> https://github.com/stefanha/qemu/commits/block
> 
> Stefan
> 



Hi,

the patch breaks hard disk i/o: a 64 bit executable built with MinGW-w64
will no longer boot a ReactOS image (BIOS fails to detect a bootable
disk). Booting a Linux CDROM seems to work and is indeed much faster.

Regards
Stefan