From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from [140.186.70.92] (port=57975 helo=eggs.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1OOD77-0004af-Oy for qemu-devel@nongnu.org; Mon, 14 Jun 2010 13:06:22 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.69) (envelope-from ) id 1OOD75-0000f1-9l for qemu-devel@nongnu.org; Mon, 14 Jun 2010 13:06:20 -0400 Received: from mail-yx0-f173.google.com ([209.85.213.173]:56428) by eggs.gnu.org with esmtp (Exim 4.69) (envelope-from ) id 1OOD75-0000ew-7b for qemu-devel@nongnu.org; Mon, 14 Jun 2010 13:06:19 -0400 Received: by yxn35 with SMTP id 35so846853yxn.4 for ; Mon, 14 Jun 2010 10:06:17 -0700 (PDT) Message-ID: <4C166187.2080805@codemonkey.ws> Date: Mon, 14 Jun 2010 12:06:15 -0500 From: Anthony Liguori MIME-Version: 1.0 Subject: Re: [Qemu-devel] [PATCH] Fix and simplify gui timer logic. References: <1275659074-4516-1-git-send-email-kraxel@redhat.com> <201006071712.52267.paul@codesourcery.com> <4C0E0CC0.80609@redhat.com> <201006081250.18942.paul@codesourcery.com> <4C0E4323.90808@redhat.com> In-Reply-To: <4C0E4323.90808@redhat.com> Content-Type: text/plain; charset=ISO-8859-15; format=flowed Content-Transfer-Encoding: 7bit List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Gerd Hoffmann Cc: Paul Brook , qemu-devel@nongnu.org On 06/08/2010 08:18 AM, Gerd Hoffmann wrote: > 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 ... Agreed. Regardless of the periodic mmio flush, having a separate nographic timer isn't terribly helpful IMHO. Regards, Anthony Liguori > cheers, > Gerd > > >