The patch titled
Subject: hrtimers: Special-case zero length sleeps
has been removed from the -mm tree. Its filename was
hrtimers-special-case-zero-length-sleeps.patch
This patch was dropped because it was nacked
The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/
------------------------------------------------------
From: Matthew Garrett <mjg@xxxxxxxxxx>
Subject: hrtimers: Special-case zero length sleeps
sleep(0) is a common construct used by applications that want to trigger
the scheduler. sched_yield() might make more sense, but only appeared in
POSIX.1-2001 and so plenty of example code still uses the sleep(0) form.
This wouldn't normally be a problem, but it means that event-driven
applications that are merely trying to avoid starving other processes may
actually end up sleeping due to having large timer_slack values. Special-
casing this seems reasonable.
Signed-off-by: Matthew Garrett <mjg@xxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Arjan van de Ven <arjan@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
kernel/hrtimer.c | 8 ++++++++
1 file changed, 8 insertions(+)
diff -puN kernel/hrtimer.c~hrtimers-special-case-zero-length-sleeps kernel/hrtimer.c
--- a/kernel/hrtimer.c~hrtimers-special-case-zero-length-sleeps
+++ a/kernel/hrtimer.c
@@ -1568,6 +1568,14 @@ long hrtimer_nanosleep(struct timespec *
if (rt_task(current))
slack = 0;
+ /*
+ * Applications will often sleep(0) to indicate that they wish to
+ * be scheduled. Special case that to avoid actually putting them
+ * to sleep for the duration of the slack.
+ */
+ if (rqtp->tv_sec == 0 && rqtp->tv_nsec == 0)
+ slack = 0;
+
hrtimer_init_on_stack(&t.timer, clockid, mode);
hrtimer_set_expires_range_ns(&t.timer, timespec_to_ktime(*rqtp), slack);
if (do_nanosleep(&t, mode))
_
Patches currently in -mm which might be from mjg@xxxxxxxxxx are
origin.patch
linux-next.patch
acerhdf-add-support-for-aspire-1410-bios-v13314.patch
acerhdf-add-support-for-new-hardware.patch
acerhdf-lowered-default-temp-fanon-fanoff-values.patch
arch-x86-platform-iris-irisc-register-a-platform-device-and-a-platform-driver.patch
x86-olpc-xo15-sci-enable-lid-close-wakeup-control-through-sysfs.patch
geos-platform-driver-for-geos-and-geos2-single-board-computers.patch
platform-drivers-x86-convert-drivers-platform-x86-to-use-module_platform_driver.patch
drivers-platform-x86-sony-laptopc-fix-scancodes.patch
platform-x86-kill-off-moorestown.patch
intel_scu_ipc-remove-moorestown-support.patch
platform-x86-intel_mid_thermal-add-msic_thermal-alias.patch
platform-x86-intel_mid_thermal-convert-to-use-intel-msic-api.patch
platform-x86-intel_mid_thermal-turn-off-thermistor-voltage-by-default.patch
intel_mid_powerbtn-use-msic-read-write-instead-of-ipc_scu.patch
intel_mid_powerbtn-mark-irq-as-irqf_no_suspend.patch
drivers-platform-x86-acer-wmic-no-wifi-rfkill-on-lenovo-machines.patch
alix2-supplement-driver-to-include-gpio-button-support.patch
net5501-platform-driver-for-soekris-engineering-net5501-single-board-computer.patch
ipmi-increase-kcs-timeouts.patch
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