Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932479AbWEPSNg (ORCPT ); Tue, 16 May 2006 14:13:36 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932490AbWEPSNf (ORCPT ); Tue, 16 May 2006 14:13:35 -0400 Received: from py-out-1112.google.com ([64.233.166.183]:27833 "EHLO py-out-1112.google.com") by vger.kernel.org with ESMTP id S932479AbWEPSNf convert rfc822-to-8bit (ORCPT ); Tue, 16 May 2006 14:13:35 -0400 DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=beta; d=gmail.com; h=received:message-id:date:from:to:subject:cc:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references; b=cKa9HS5eLBBHoKFqDPDljjlvPDVeKRx3sX/OwW+YXT83mLwKRo0dpN7Kz3X/oOHAOveHN3IM6MDu0InaQMuzizVK5fdtrGy9eDtcuxWF7MZKyV8GVpaKklkMV4iVazlDaJovhc4elyM6FxhxItG/GlR75rM/1xDsYnqNYfpU/OI= Message-ID: <3b0ffc1f0605161113j321e1e36l9de8bf6eacbc0b49@mail.gmail.com> Date: Tue, 16 May 2006 14:13:31 -0400 From: "Kevin Radloff" To: "Tejun Heo" Subject: Re: PATCH: Fix broken PIO with libata Cc: "Jeff Garzik" , "Alan Cox" , linux-kernel@vger.kernel.org In-Reply-To: <446A0E36.5060505@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII; format=flowed Content-Transfer-Encoding: 7BIT Content-Disposition: inline References: <1147790393.2151.62.camel@localhost.localdomain> <3b0ffc1f0605160833k5f6355c5n3f2a9ab1b211a95@mail.gmail.com> <1147794791.2151.71.camel@localhost.localdomain> <3b0ffc1f0605161019j7149f72bv309db19eb9d12dd8@mail.gmail.com> <446A0B6C.8050901@garzik.org> <446A0E36.5060505@gmail.com> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1683 Lines: 40 On 5/16/06, Tejun Heo wrote: > Jeff Garzik wrote: > > Kevin Radloff wrote: > >> On 5/16/06, Alan Cox wrote: > >>> On Maw, 2006-05-16 at 11:33 -0400, Kevin Radloff wrote: > >>> > However, I still have a problem with pata_pcmcia (that I actually > >>> > experienced also with the ide-cs driver) where sustained reading or > >>> > writing to the CF card spikes the CPU with nearly 100% system time. > >>> > >>> That is normal. The PCMCIA devices don't support DMA. As a result of > >>> this the processor has to fetch each byte itself over the ISA speed > >>> PCMCIA bus link. > >> > >> Hrm, as I recall that only started happening with ide-cs sometime in > >> the single digits of 2.6.x.. And note that it's only maxing out at > >> about 1.5MB/s. Should that saturate my laptop's 1.1GHz Pentium M > >> processor? > > > > Doing data xfer using PIO rather than DMA definitely eats tons of CPU > > cycles. > > Yeap, in addition, if doing real PIO (unbuffered by the HBA), the time > it takes is soley determined by what PIO mode is in use. It doesn't > matter how fast the CPU is. Faster CPUs only end up wasting more > cycles. :-( (oops, hit 'reply', but given the incredible importance of my response... ;P) Ah, well then never mind. ;) I just have a dim memory of it being different a long time ago. At least it works now. :D -- Kevin 'radsaq' Radloff radsaq@gmail.com http://thesaq.com/ - 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/