Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Tue, 9 Apr 2002 16:05:16 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Tue, 9 Apr 2002 16:05:15 -0400 Received: from mailf.telia.com ([194.22.194.25]:32203 "EHLO mailf.telia.com") by vger.kernel.org with ESMTP id ; Tue, 9 Apr 2002 16:05:15 -0400 Content-Type: text/plain; charset="iso-8859-1" From: Roger Larsson (by way of Roger Larsson ) Subject: Re: PROMBLEM: CD burning at 16x uses excessive CPU, although DMA is enabled Date: Tue, 9 Apr 2002 22:06:02 +0200 X-Mailer: KMail [version 1.4] To: Anssi Saari Cc: linux-kernel@vger.kernel.org, Mark Mielke MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Message-Id: <200204092206.02376.roger.larsson@norran.net> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On tisdagen den 9 april 2002 12.01, Anssi Saari wrote: > On Mon, Apr 08, 2002 at 06:02:55PM -0400, Mark Hahn wrote: > > I think someone else already pointed out that doing > > a kernel profile would be good. strace would also > > be quite useful, even just the -c form. > > Here it is: > > With unmaskirq=1 first: > > > 49 handle_IRQ_event 0.5104 > 239 file_read_actor 2.4896 > 3324 default_idle 69.2500 > 20097 ide_output_data 104.6719 Hey, what is this? Comment of the function is: "This is used for most PIO data transfers *to* the IDE interface" (see /drivers/ide/ide.c:426) Has it reverted to PIO mode? Some information might be found with # more /proc/ide/hd*/settings This is how mine look like cat /proc/ide/hdc/settings name value min max mode ---- ----- --- --- ---- bios_cyl 0 0 1023 rw bios_head 0 0 255 rw bios_sect 0 0 63 rw current_speed 66 0 69 rw ide_scsi 0 0 1 rw init_speed 66 0 69 rw io_32bit 0 0 3 rw keepsettings 0 0 1 rw log 0 0 1 rw nice1 1 0 1 rw number 2 0 3 rw pio_mode write-only 0 255 w slow 0 0 1 rw transform 1 0 3 rw unmaskirq 1 0 1 rw using_dma 1 0 1 rw > 23952 total 0.0236 > Number of interrupts on ide1 during burn: 17531 > > And then, unmaskirq=0: > > - - - > 168 do_softirq 0.9545 > 234 file_read_actor 2.4375 > 1942 handle_IRQ_event 20.2292 > 2949 default_idle 61.4375 > 6808 ide_intr 18.5000 > 12333 total 0.0122 > Number of interrupts on ide1 during burn: 17532 This looks like mine results. Quite some time spent in interrupt routines. (weighted 38%) Using or not using unmaskirq does not matter for me: It stays below 40%, but I do only run at 10x (40% is quite much for any disk bound operation...) I will attempt a profiling while unmasked too. I assume you also use ide_scsi, right? /RogerL -- Roger Larsson Skellefte? Sweden - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/