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From: | Gerd Hoffmann |
Subject: | Re: [Qemu-devel] [PATCH] Fix and simplify gui timer logic. |
Date: | Tue, 08 Jun 2010 15:18:27 +0200 |
User-agent: | Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.9) Gecko/20100430 Fedora/3.0.4-2.fc12 Thunderbird/3.0.4 |
On 06/08/10 13:50, Paul Brook wrote:
Kill nographic timer. Have a global gui_timer instead. Have the gui timer enabled unconditionally. We need a timer running anyway for mmio flush, so the whole have-gui-timer-only-when-needed logic is pretty pointless. It also simplifies displaylisteners coming and going at runtime, we don't need to care about the timer then as it runs anyway.Linking mmio flushes to the gui is completely bogus. The fact that we're doing arbitrary periodic mmio flushes suggests something else is horribly broken.Was added by commit http://git.qemu.org/qemu.git/commit/?id=62a2744ca09a0b44b8406ea0c430c4c67a2 c3231 Patch description makes sense to me. Of course we could have a separate timer for the mmio flushes instead of re-using the gui timer. But we would have more wakeups then ...This suggests we are incorrectly coalescing writes, and we should actually be notifying qemu when (at least) he first write occurs. If we aren't outputting anything we don't want to be waking up periodically just to flush an empty MMIO buffer.
That is completely unrelated to this patch though. The patch doesn't change mmio flush behaviour at all. And the periodic wakeup was there even before the mmio flush patch was added. Even without gui, although I can't see a obvious reason for it ...
cheers, Gerd
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