From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932869Ab0EJXih (ORCPT ); Mon, 10 May 2010 19:38:37 -0400 Received: from kroah.org ([198.145.64.141]:33097 "EHLO coco.kroah.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932398Ab0EJWwJ (ORCPT ); Mon, 10 May 2010 18:52:09 -0400 X-Mailbox-Line: From gregkh@kvm.kroah.org Mon May 10 15:33:21 2010 Message-Id: <20100510223321.078509558@kvm.kroah.org> User-Agent: quilt/0.48-4.4 Date: Mon, 10 May 2010 15:32:14 -0700 From: Greg KH To: linux-kernel@vger.kernel.org, stable@kernel.org Cc: stable-review@kernel.org, torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, NeilBrown , Dan Williams Subject: [043/117] raid6: fix recovery performance regression In-Reply-To: <20100510223700.GA18404@kroah.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 2.6.33-stable review patch. If anyone has any objections, please let us know. ------------------ From: Dan Williams commit 5157b4aa5b7de8787b6318e61bcc285031bb9088 upstream. The raid6 recovery code should immediately drop back to the optimized synchronous path when a p+q dma resource is not available. Otherwise we run the non-optimized/multi-pass async code in sync mode. Verified with raid6test (NDISKS=255) Applies to kernels >= 2.6.32. Acked-by: NeilBrown Reported-by: H. Peter Anvin Signed-off-by: Dan Williams Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- crypto/async_tx/async_raid6_recov.c | 21 +++++++++++++-------- 1 file changed, 13 insertions(+), 8 deletions(-) --- a/crypto/async_tx/async_raid6_recov.c +++ b/crypto/async_tx/async_raid6_recov.c @@ -324,6 +324,7 @@ struct dma_async_tx_descriptor * async_raid6_2data_recov(int disks, size_t bytes, int faila, int failb, struct page **blocks, struct async_submit_ctl *submit) { + void *scribble = submit->scribble; int non_zero_srcs, i; BUG_ON(faila == failb); @@ -332,11 +333,13 @@ async_raid6_2data_recov(int disks, size_ pr_debug("%s: disks: %d len: %zu\n", __func__, disks, bytes); - /* we need to preserve the contents of 'blocks' for the async - * case, so punt to synchronous if a scribble buffer is not available + /* if a dma resource is not available or a scribble buffer is not + * available punt to the synchronous path. In the 'dma not + * available' case be sure to use the scribble buffer to + * preserve the content of 'blocks' as the caller intended. */ - if (!submit->scribble) { - void **ptrs = (void **) blocks; + if (!async_dma_find_channel(DMA_PQ) || !scribble) { + void **ptrs = scribble ? scribble : (void **) blocks; async_tx_quiesce(&submit->depend_tx); for (i = 0; i < disks; i++) @@ -406,11 +409,13 @@ async_raid6_datap_recov(int disks, size_ pr_debug("%s: disks: %d len: %zu\n", __func__, disks, bytes); - /* we need to preserve the contents of 'blocks' for the async - * case, so punt to synchronous if a scribble buffer is not available + /* if a dma resource is not available or a scribble buffer is not + * available punt to the synchronous path. In the 'dma not + * available' case be sure to use the scribble buffer to + * preserve the content of 'blocks' as the caller intended. */ - if (!scribble) { - void **ptrs = (void **) blocks; + if (!async_dma_find_channel(DMA_PQ) || !scribble) { + void **ptrs = scribble ? scribble : (void **) blocks; async_tx_quiesce(&submit->depend_tx); for (i = 0; i < disks; i++)