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Filename Latest commit message Latest commit date
Adrian Hunter c724eb78c1 mmc: sdio: Use mmc_pre_req() / mmc_post_req()
commit f0c393e2104e48c8a881719a8bd37996f71b0aee upstream.

SDHCI changed from using a tasklet to finish requests, to using an IRQ
thread i.e. commit c07a48c265 ("mmc: sdhci: Remove finish_tasklet").
Because this increased the latency to complete requests, a preparatory
change was made to complete the request from the IRQ handler if
possible i.e. commit 19d2f695f4 ("mmc: sdhci: Call mmc_request_done()
from IRQ handler if possible").  That alleviated the situation for MMC
block devices because the MMC block driver makes use of mmc_pre_req()
and mmc_post_req() so that successful requests are completed in the IRQ
handler and any DMA unmapping is handled separately in mmc_post_req().
However SDIO was still affected, and an example has been reported with
up to 20% degradation in performance.

Looking at SDIO I/O helper functions, sdio_io_rw_ext_helper() appeared
to be a possible candidate for making use of asynchronous requests
within its I/O loops, but analysis revealed that these loops almost
never iterate more than once, so the complexity of the change would not
be warrented.

Instead, mmc_pre_req() and mmc_post_req() are added before and after I/O
submission (mmc_wait_for_req) in mmc_io_rw_extended().  This still has
the potential benefit of reducing the duration of interrupt handlers, as
well as addressing the latency issue for SDHCI.  It also seems a more
reasonable solution than forcing drivers to do everything in the IRQ
handler.

Reported-by: Dmitry Osipenko <digetx@gmail.com>
Fixes: c07a48c265 ("mmc: sdhci: Remove finish_tasklet")
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Tested-by: Dmitry Osipenko <digetx@gmail.com>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20200903082007.18715-1-adrian.hunter@intel.com
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-09-17 13:47:53 +02:00
arch arm64/module: set trampoline section flags regardless of CONFIG_DYNAMIC_FTRACE 2020-09-17 13:47:49 +02:00
block block: Set same_page to false in __bio_try_merge_page if ret is false 2020-09-17 13:47:44 +02:00
certs
crypto crypto: af_alg - Work around empty control messages without MSG_MORE 2020-09-03 11:27:05 +02:00
Documentation affs: fix basic permission bits to actually work 2020-09-09 19:12:34 +02:00
drivers mmc: sdio: Use mmc_pre_req() / mmc_post_req() 2020-09-17 13:47:53 +02:00
fs btrfs: fix wrong address when faulting in pages in the search ioctl 2020-09-17 13:47:52 +02:00
include irqchip/eznps: Fix build error for !ARC700 builds 2020-09-17 13:47:47 +02:00
init x86: Fix early boot crash on gcc-10, third try 2020-05-20 08:20:34 +02:00
ipc
kernel gcov: Disable gcov build with GCC 10 2020-09-17 13:47:49 +02:00
lib kobject: Restore old behaviour of kobject_del(NULL) 2020-09-17 13:47:52 +02:00
LICENSES
mm mm/khugepaged.c: fix khugepaged's request size in collapse_file 2020-09-09 19:12:37 +02:00
net cfg80211: Adjust 6 GHz frequency to channel conversion 2020-09-17 13:47:46 +02:00
samples bpf: Fix fds_example SIGSEGV error 2020-08-19 08:16:03 +02:00
scripts checkpatch: fix the usage of capture group ( ... ) 2020-09-09 19:12:37 +02:00
security Smack: prevent underflow in smk_set_cipso() 2020-08-19 08:16:16 +02:00
sound ALSA: hda: fix a runtime pm issue in SOF when integrated GPU is disabled 2020-09-17 13:47:49 +02:00
tools selftests/timers: Turn off timeout setting 2020-09-17 13:47:41 +02:00
usr
virt KVM: arm64: Only reschedule if MMU_NOTIFIER_RANGE_BLOCKABLE is not set 2020-08-26 10:41:08 +02:00
.clang-format
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore
.mailmap
COPYING
CREDITS
Kbuild
Kconfig
MAINTAINERS Documentation/llvm: add documentation on building w/ Clang/LLVM 2020-08-26 10:40:46 +02:00
Makefile Linux 5.4.65 2020-09-12 14:18:56 +02:00
README

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.