Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752861AbbEKJPH (ORCPT ); Mon, 11 May 2015 05:15:07 -0400 Received: from down.free-electrons.com ([37.187.137.238]:39531 "EHLO mail.free-electrons.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752386AbbEKJPE (ORCPT ); Mon, 11 May 2015 05:15:04 -0400 Date: Mon, 11 May 2015 11:13:35 +0200 From: Maxime Ripard To: Markus Stockhausen Cc: Neil Brown , Shaohua Li , "linux-raid@vger.kernel.org" , "linux-kernel@vger.kernel.org" , Lior Amsalem , Thomas Petazzoni , Gregory Clement , Boris Brezillon Subject: Re: Possible RAID6 regression with ASYNC_TX_DMA enabled in 4.1 Message-ID: <20150511091335.GA10961@lukather> References: <20150507125702.GI11057@lukather> <12EF8D94C6F8734FB2FF37B9FBEDD1735FC9B959@EXCHANGE.collogia.de> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="cWoXeonUoKmBZSoM" Content-Disposition: inline In-Reply-To: <12EF8D94C6F8734FB2FF37B9FBEDD1735FC9B959@EXCHANGE.collogia.de> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3994 Lines: 108 --cWoXeonUoKmBZSoM Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable Hi Markus, On Thu, May 07, 2015 at 02:39:07PM +0000, Markus Stockhausen wrote: > Hi Maxime, >=20 > > Von: linux-raid-owner@vger.kernel.org [linux-raid-owner@vger.kernel.org= ]" im Auftrag von "Maxime Ripard [maxime.ripard@free-electrons.co= m] > > Gesendet: Donnerstag, 7. Mai 2015 14:57 > > An: Neil Brown; Shaohua Li > > Cc: linux-raid@vger.kernel.org; linux-kernel@vger.kernel.org; Lior Amsa= lem; Thomas Petazzoni; Gregory Clement; Boris Brezillon > > Betreff: Possible RAID6 regression with ASYNC_TX_DMA enabled in 4.1 > >=20 > > Hi, > >=20 > > I'm currently trying to add support for the PQ operations on the > > marvell XOR engine, in dmaengine, obviously to be able to use async_tx > > to offload these operations. > >=20 > > I'm testing these patches with a RAID6 array with 4 disks. > >=20 > > However, since the commit 59fc630b8b5f ("RAID5: batch adjacent full > > stripe write", every write to that array fails with the following > > stacktrace. > >=20 > > http://code.bulix.org/eh8iew-88342?raw >=20 > I don't know if it might be related. I added support for RAID6 Read-Modif= y-Write > in software XOR with some patches. The following commit mangles some line= s in=20 > async_pq.c: >=20 > https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/? > id=3D584acdd49cd2472ca0f5a06adbe979db82d0b4af >=20 > I introduced a new flag ASYNC_TX_PQ_XOR_DST that notifies the async layer > that we want to do a XOR syndrome operation instead of a full calculation. > This will enforce the software path because I guessed that hardware does = not > support that case. Without hardware to check I might have missed some=20 > checks in the async layer. >=20 > In the upper layer ops_run_reconstruct6 will set the flag if we determined > that rmw is faster than rcw. >=20 > Can you check if rmw_level=3D0 fixes the issue. See: >=20 > https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/? > id=3Dd06f191f8ecaef4d524e765fdb455f96392fbd42 I just gave this a try, and it doesn't fix anything. One thing I forgot to mention is that our hardware doesn't support the PQ multiplications and product sums, so one of the patches we have is to add a new ASYNC_TX flag to be able to identify and bail out of such transfers. The patch is here: https://github.com/MISL-EBU-System-SW/mainline-public/commit/9964fe4a79da10= 162f83bd527b3fe44da60d7e0f There might be some interaction between your patch and this one, even though the async_tx code itself looks to be untouched by your patches. Thanks! Maxime --=20 Maxime Ripard, Free Electrons Embedded Linux, Kernel and Android engineering http://free-electrons.com --cWoXeonUoKmBZSoM Content-Type: application/pgp-signature; name="signature.asc" Content-Description: Digital signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 iQIcBAEBAgAGBQJVUHK/AAoJEBx+YmzsjxAgwPIP/jzHlKeiKVM48cOppT+6xF94 UXp9L98ccmLCxLT4dHAuB1+X4J5aX8a1pFkh4Zi5VFycGK13Sfrlf//u9ivPT2Px H0qXBKkTStJTftrDMzfyYbS0JPhx+e2YwQIoI6kGpLHn+qmP6TMsbHh7hhrGrq07 XJMlnoaZGqZGk2rQNl2wF6O2IiyT3qKSnkarbXpPOrpj4iMKlTyRrO53tce0s6TR yf3EUM7SeLNM00ByLH0wFK0VxU35HJuDW+SgalS2OnqsSMAmKsO4l+lk8EmjLrpo feg8Pyy20cn0zeWwETg5e64SFaqFZf+VLxj6070yYvLb7hD//DyMo1e/j+poDyyx ESK81DMmAEYl7LE7J3KMLFSJK00aTcKjX3td2rt8sw3F++6MWXx80IR+FL8us8oa sTLIQTcJALr4WFxdmIpE+YzuGHkAMGManpdjG25GJfY7H5ERCUZw/XDz/r4C9YX6 tV1MnweVUaEONcrB8RW4ADROMNKMvvrGnO/GSl8hM0MTTaPENZMWO+ePHkbTwE7U TDJgUr2firFAYQFeIAWqJDAMECY2HhfZTiu4dwUj0TaUbrBC0jfbMrQ6h+tXeCYg uz2uL6fo7QvQeMne0uny404sn08mnSSv+DrS+Vmg65X7UWKXI8TODgZrlyinSNl3 xH26X14mhq/zZc4KeO0T =0m98 -----END PGP SIGNATURE----- --cWoXeonUoKmBZSoM-- -- 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/