From mboxrd@z Thu Jan 1 00:00:00 1970 From: Pavel Machek Date: Thu, 23 Jun 2011 19:03:28 +0000 Subject: Re: [PATCH 1/3] printk: Release console_sem after logbuf_lock Message-Id: <20110623190327.GA607@localhost.ucw.cz> List-Id: References: <20110609130647.937204592@chello.nl> <20110609131307.493181962@chello.nl> <20110609130617.f8aca966.akpm@linux-foundation.org> <20110609202707.GA28951@elte.hu> <1307652883.2497.1028.camel@laptop> <20110609140714.fc9ea187.akpm@linux-foundation.org> <1307705311.3941.118.camel@twins> <1307709030.3941.134.camel@twins> In-Reply-To: <1307709030.3941.134.camel@twins> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Peter Zijlstra Cc: Hugh Dickins , Andrew Morton , Ingo Molnar , Linus Torvalds , Thomas Gleixner , linux-kernel@vger.kernel.org, efault@gmx.de, Arne Jansen , PaulMundt , linux-fbdev@vger.kernel.org vvOn Fri 2011-06-10 14:30:30, Peter Zijlstra wrote: >On Fri, 2011-06-10 at 13:28 +0200, Peter Zijlstra wrote: > > On Thu, 2011-06-09 at 16:57 -0700, Hugh Dickins wrote: > > > > > > All console-related activity curently happens under spin_lock_irqsave(&console_lock). > > > This causes interrutps to be blocked for 1-2 milliseconds with vgacon, and for > > > hundreds of milliseconds with fbdevs. This results in network overruns, audio > > > dropouts, dropped characters on serial ports and other such nice things. > > > > Hmm, with these proposed patches we're actually back to that. I wonder > > if fbdev is still that crappy.. > > So I tried adding a fbcon to my test box (not that it actually has a > display, but who cares) and disabled lockdep (otherwise that's all I can > catch on the latency tracer) to see if I could see whopping horrid > latencies there, but I'm afraid I either failed to set things up > properly or my fbcon isn't sucky enough. > > What I did was enable: > > CONFIG_FB=y > CONFIG_FB_SIS=y > CONFIG_FB_SIS_315=y (the board has XGI z7) sis will be accelerated. Try vesafb; scrolling should be horrible. -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html