From mboxrd@z Thu Jan 1 00:00:00 1970 From: Linda Walsh Subject: Re: Port Multiplier access with Sil 3124 Date: Mon, 09 Feb 2009 14:01:37 -0800 Message-ID: <4990A7C1.5060904@tlinx.org> References: <498F42B6.8030607@tlinx.org> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from ishtar.tlinx.org ([64.81.245.74]:37110 "EHLO ishtar.tlinx.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752799AbZBIWBq (ORCPT ); Mon, 9 Feb 2009 17:01:46 -0500 In-Reply-To: Sender: linux-ide-owner@vger.kernel.org List-Id: linux-ide@vger.kernel.org To: Grant Grundler Cc: linux-ide@vger.kernel.org Grant Grundler wrote: > Linda, > Please tell us which kernel version you have and include the dmesg > output. Port multiplier support is generally working in 2.6.26 (and later > releases) for several drivers. PM support was added after 2.6.20. --- Sorry. I'm a bit behind the edge at 2.6.27.3 -- but I tried a boot w/2.6.28.3 and didn't see a difference (had to return to 27.3 as I accidently disabled a different driver and haven't regened it. > > Where did you find 350MB/s theoretical? > Link is 8b10b encoded. So it's 10:1 of bits to bytes conversion of link rate. > 3Gb/s --> 300MB/s in theory. --- Yep. Forgot about that... was forgetting about the 2-bits of overhead, so was using 3Gb/8/(1024*1024) -> 357.6, which I rounded down to 350... but forgot about the 10/8 encoding (just as I get rid of that conversion habit from modem days, now I have to remember it as a special case for SATA...:-) ). > > For MB/s, it depends on the SATA controller. Don't expect more then > 225-235 MB/s per port. At least one sata_sil3124 chip (3126?) is buggy > and won't do more than 120MB/s read for all ports (170 MB/s write). > See linux-ide archives for discussion on this. --- That's horrible! I'd definitely call that a bug. Right now, the fastest I'm getting on my single ATA's is 70-80MB/s. I could get that per/ATA port. So 120MB read for 4 SATA ports would be a giant step backwards (170MB/s write? write faster than read?)