linux-kernel - [PATCH v2 2/2] dmaengine: ioat: Decreasing allocation chunk size 2M -> 512K

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Date:   Thu,  2 Apr 2020 19:33:43 +0300
From:   leonid.ravich@...l.com
To:     dmaengine@...r.kernel.org
Cc:     lravich@...il.com, Leonid Ravich <Leonid.Ravich@...l.com>,
        Vinod Koul <vkoul@...nel.org>,
        Dan Williams <dan.j.williams@...el.com>,
        Dave Jiang <dave.jiang@...el.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Alexios Zavras <alexios.zavras@...el.com>,
        "Alexander.Barabash@...l.com" <Alexander.Barabash@...l.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Kate Stewart <kstewart@...uxfoundation.org>,
        Jilayne Lovejoy <opensource@...ayne.com>,
        Logan Gunthorpe <logang@...tatee.com>,
        linux-kernel@...r.kernel.org
Subject: [PATCH v2 2/2] dmaengine: ioat: Decreasing  allocation chunk size 2M -> 512K

From: Leonid Ravich <Leonid.Ravich@....com>

current IOAT driver using big (2MB) allocations chunk for its descriptors
therefore each ioat dma engine need 2 such chunks
(64k entres in ring  each entry 64B = 4MB)
requiring 2 * 2M * dmaengine contiguies memory chunk
might fail due to memory fragmention.

so we decreasing chunk size and using more chunks.

Acked-by: Dave Jiang <dave.jiang@...el.com>
Signed-off-by: Leonid Ravich <Leonid.Ravich@....com>
---
 drivers/dma/ioat/dma.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/dma/ioat/dma.h b/drivers/dma/ioat/dma.h
index 5216c6b..e6b622e 100644
--- a/drivers/dma/ioat/dma.h
+++ b/drivers/dma/ioat/dma.h
@@ -83,7 +83,7 @@ struct ioatdma_device {
 
 #define IOAT_MAX_ORDER 16
 #define IOAT_MAX_DESCS (1 << IOAT_MAX_ORDER)
-#define IOAT_CHUNK_SIZE (SZ_2M)
+#define IOAT_CHUNK_SIZE (SZ_512K)
 #define IOAT_DESCS_PER_CHUNK (IOAT_CHUNK_SIZE / IOAT_DESC_SZ)
 
 struct ioat_descs {
-- 
1.9.3