@@ -62,8 +62,7 @@ MODULE_ALIAS("mmc:block");
#define MMC_SANITIZE_REQ_TIMEOUT 240000
#define MMC_EXTRACT_INDEX_FROM_ARG(x) ((x & 0x00FF0000) >> 16)
-#define mmc_req_rel_wr(req) (((req->cmd_flags & REQ_FUA) || \
- (req->cmd_flags & REQ_META)) && \
+#define mmc_req_rel_wr(req) ((req->cmd_flags & REQ_FUA) && \
(rq_data_dir(req) == WRITE))
#define PACKED_CMD_VER 0x01
#define PACKED_CMD_WR 0x02
@@ -1377,13 +1376,9 @@ static void mmc_blk_rw_rq_prep(struct mmc_queue_req *mqrq,
/*
* Reliable writes are used to implement Forced Unit Access and
- * REQ_META accesses, and are supported only on MMCs.
- *
- * XXX: this really needs a good explanation of why REQ_META
- * is treated special.
+ * are supported only on MMCs.
*/
- bool do_rel_wr = ((req->cmd_flags & REQ_FUA) ||
- (req->cmd_flags & REQ_META)) &&
+ bool do_rel_wr = (req->cmd_flags & REQ_FUA) &&
(rq_data_dir(req) == WRITE) &&
(md->flags & MMC_BLK_REL_WR);
This is a note to let you know that I have just added a patch titled mmc: remove bondage between REQ_META and reliable write to the linux-4.2.y-queue branch of the 4.2.y-ckt extended stable tree which can be found at: http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-4.2.y-queue This patch is scheduled to be released in version 4.2.8-ckt2. If you, or anyone else, feels it should not be added to this tree, please reply to this email. For more information about the 4.2.y-ckt tree, see https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable Thanks. -Kamal ---8<------------------------------------------------------------ From c9394e4abc0c7b0d4d7909d527b83d9cdb16df5e Mon Sep 17 00:00:00 2001 From: Luca Porzio <lporzio@micron.com> Date: Fri, 6 Nov 2015 15:12:26 +0000 Subject: mmc: remove bondage between REQ_META and reliable write commit d3df0465db00cf4ed9f90d0bfc3b827d32b9c796 upstream. Anytime a write operation is performed with Reliable Write flag enabled, the eMMC device is enforced to bypass the cache and do a write to the underling NVM device by Jedec specification; this causes a performance penalty since write operations can't be optimized by the device cache. In our tests, we replayed a typical mobile daily trace pattern and found ~9% overall time reduction in trace replay by using this patch. Also the write ops within 4KB~64KB chunk size range get a 40~60% performance improvement by using the patch (as this range of write chunks are the ones affected by REQ_META). This patch has been discussed in the Mobile & Embedded Linux Storage Forum and it's the results of feedbacks from many people. We also checked with fsdevl and f2fs mailing list developers that this change in the usage of REQ_META is not affecting FS behavior and we got positive feedbacks. Reporting here the feedbacks: http://comments.gmane.org/gmane.linux.file-systems/97219 http://thread.gmane.org/gmane.linux.file-systems.f2fs/3178/focus=3183 Signed-off-by: Bruce Ford <bford@micron.com> Signed-off-by: Luca Porzio <lporzio@micron.com> Fixes: ce39f9d17c14 ("mmc: support packed write command for eMMC4.5 devices") Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org> Signed-off-by: Kamal Mostafa <kamal@canonical.com> --- drivers/mmc/card/block.c | 11 +++-------- 1 file changed, 3 insertions(+), 8 deletions(-) -- 1.9.1