From 5157b4aa5b7de8787b6318e61bcc285031bb9088 Mon Sep 17 00:00:00 2001 From: Dan Williams Date: Tue, 4 May 2010 20:41:56 -0700 Subject: [PATCH] raid6: fix recovery performance regression 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. Cc: Acked-by: NeilBrown Reported-by: H. Peter Anvin Signed-off-by: Dan Williams Signed-off-by: Linus Torvalds --- crypto/async_tx/async_raid6_recov.c | 21 +++++++++++++-------- 1 file changed, 13 insertions(+), 8 deletions(-) diff --git a/crypto/async_tx/async_raid6_recov.c b/crypto/async_tx/async_raid6_recov.c index 943f2abac9b4..ce038d861eb9 100644 --- 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_t bytes, int faila, int failb, 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_t bytes, int faila, 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++) -- 2.20.1