Dan Williams
8a4aeec8d2
libata/ahci: accommodate tag ordered controllers ...
The AHCI spec allows implementations to issue commands in tag order
rather than FIFO order:
5.3.2.12 P:SelectCmd
HBA sets pSlotLoc = (pSlotLoc + 1) mod (CAP.NCS + 1)
or HBA selects the command to issue that has had the
PxCI bit set to '1' longer than any other command
pending to be issued.
The result is that commands posted sequentially (time-wise) may play out
of sequence when issued by hardware.
This behavior has likely been hidden by drives that arrange for commands
to complete in issue order. However, it appears recent drives (two from
different vendors that we have found so far) inflict out-of-order
completions as a matter of course. So, we need to take care to maintain
ordered submission, otherwise we risk triggering a drive to fall out of
sequential-io automation and back to random-io processing, which incurs
large latency and degrades throughput.
This issue was found in simple benchmarks where QD=2 seq-write
performance was 30-50% *greater* than QD=32 seq-write performance.
Tagging for -stable and making the change globally since it has a low
risk-to-reward ratio. Also, word is that recent versions of an unnamed
OS also does it this way now. So, drives in the field are already
experienced with this tag ordering scheme.
Cc: <stable@vger.kernel.org>
Cc: Dave Jiang <dave.jiang@intel.com>
Cc: Ed Ciechanowski <ed.ciechanowski@intel.com>
Reviewed-by: Matthew Wilcox <matthew.r.wilcox@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
2014-04-18 15:56:03 -04:00
PCI changes for the v3.15 merge window:
2014-04-01 15:14:04 -07:00
libata/ahci: accommodate tag ordered controllers
2014-04-18 15:56:03 -04:00
Driver core / sysfs patches for 3.15-rc1
2014-04-01 16:28:19 -07:00
Merge branch 'for-3.15/drivers' of git://git.kernel.dk/linux-block
2014-04-01 19:43:53 -07:00
Single fix for a clock driver merged in 3.14-rc1. Without this fix the
2014-03-08 10:51:30 -08:00
Merge branch 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
2014-04-01 11:00:07 -07:00
ACPI and power management updates for 3.15-rc1
2014-04-01 12:48:54 -07:00
Merge branch 'for-3.15/core' of git://git.kernel.dk/linux-block
2014-04-01 19:19:15 -07:00
PM / devfreq: Rewrite devfreq_update_status() to fix multiple bugs
2014-03-21 11:16:30 +09:00
A bunch of EDAC updates all over the place:
2014-04-01 13:54:00 -07:00
extcon: Move OF helper function to extcon core and change function name
2014-03-19 14:41:58 +09:00
Merge branch 'for-3.14-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq
2014-03-08 11:51:13 -08:00
Driver core / sysfs patches for 3.15-rc1
2014-04-01 16:28:19 -07:00
Driver core / sysfs patches for 3.15-rc1
2014-04-01 16:28:19 -07:00
USB patches for 3.15-rc1
2014-04-01 17:06:09 -07:00
Char/Misc driver patches for 3.15-rc1
2014-04-01 16:13:21 -07:00
hwmon: (pmbus/ltc2978) Add support for LTM4676
2014-03-19 18:59:40 -07:00
i2c: cpm: Fix build by adding of_address.h and of_irq.h
2014-03-24 14:54:21 +01:00
Staging driver pull request for 3.15-rc1
2014-04-01 16:45:00 -07:00
Merge git://git.kernel.org/pub/scm/linux/kernel/git/nab/target-pending
2014-03-09 13:50:14 -07:00
ACPI and power management updates for 3.15-rc1
2014-04-01 12:48:54 -07:00
PCI changes for the v3.15 merge window:
2014-04-01 15:14:04 -07:00
irqchip: sun7i/sun6i: Disable NMI before registering the handler
2014-03-31 11:12:57 +02:00
isdn/capi: Make Middleware depend on CAPI2.0
2014-03-18 15:02:57 -04:00
drivers: mcb: Fix build error discovered by 0-day bot
2014-03-09 10:22:46 -07:00
Merge branch 'for-3.15/drivers' of git://git.kernel.dk/linux-block
2014-04-01 19:43:53 -07:00
Staging driver pull request for 3.15-rc1
2014-04-01 16:45:00 -07:00
PCI changes for the v3.15 merge window:
2014-04-01 15:14:04 -07:00
regulator: Updates for v3.15
2014-04-01 13:17:46 -07:00
Staging driver pull request for 3.15-rc1
2014-04-01 16:45:00 -07:00
workqueue: remove deprecated WQ_NON_REENTRANT
2014-03-29 09:33:03 -04:00
Char/Misc driver patches for 3.15-rc1
2014-04-01 16:13:21 -07:00
Merge branch 'for-3.15' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq
2014-03-31 15:08:51 -07:00
Staging driver pull request for 3.15-rc1
2014-04-01 16:45:00 -07:00
Driver core / sysfs patches for 3.15-rc1
2014-04-01 16:28:19 -07:00
PCI changes for the v3.15 merge window:
2014-04-01 15:14:04 -07:00
PHY: add APM X-Gene SoC 15Gbps Multi-purpose PHY driver
2014-03-09 12:45:13 +05:30
Pin control bulk changes for the v3.15 series, no new core
2014-04-01 13:10:49 -07:00
sound updates for 3.15-rc1
2014-04-01 15:38:47 -07:00
Merge branch 'x86-asmlinkage-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
2014-03-31 14:13:25 -07:00
Merge remote-tracking branches 'regulator/topic/tps65218', 'regulator/topic/tps6524x', 'regulator/topic/tps6586x', 'regulator/topic/tps65910', 'regulator/topic/tps80031', 'regulator/topic/wm831x', 'regulator/topic/wm8350' and 'regulator/topic/wm8994' into regulator-next
2014-03-26 16:58:25 +00:00
Driver core / sysfs patches for 3.15-rc1
2014-04-01 16:28:19 -07:00
Merge branch 'for-3.15/core' of git://git.kernel.dk/linux-block
2014-04-01 19:19:15 -07:00
Merge remote-tracking branches 'spi/topic/xilinx' and 'spi/topic/xtfpga' into spi-next
2014-03-30 00:51:48 +00:00
spmi: pm: drop bus-level PM suspend/resume routines
2014-03-08 22:15:52 -08:00
Staging driver pull request for 3.15-rc1
2014-04-01 16:45:00 -07:00
TTY/Serial driver update for 3.15-rc1
2014-04-01 16:55:57 -07:00
USB patches for 3.15-rc1
2014-04-01 17:06:09 -07:00
PCI changes for the v3.15 merge window:
2014-04-01 15:14:04 -07:00
vhost: validate vhost_get_vq_desc return value
2014-03-28 16:10:35 -04:00
Char/Misc driver patches for 3.15-rc1
2014-04-01 16:13:21 -07:00
watchdog: Fix Elan SC520 dependencies
2014-03-31 13:36:12 +02:00
ACPI and power management updates for 3.15-rc1
2014-04-01 12:48:54 -07:00
8a4aeec8d2