linux/drivers/clocksource/Kconfig

226 lines
5.4 KiB

clocksource: exynos_mct: Only use 32-bits where possible The MCT has a nice 64-bit counter. That means that we _can_ register as a 64-bit clocksource and sched_clock. ...but that doesn't mean we should. The 64-bit counter is read by reading two 32-bit registers. That means reading needs to be something like: - Read upper half - Read lower half - Read upper half and confirm that it hasn't changed. That wouldn't be terrible, but: - THe MCT isn't very fast to access (hundreds of nanoseconds). - The clocksource is queried _all the time_. In total system profiles of real workloads on ChromeOS, we've seen exynos_frc_read() taking 2% or more of CPU time even after optimizing the 3 reads above to 2 (see below). The MCT is clocked at ~24MHz on all known systems. That means that the 32-bit half of the counter rolls over every ~178 seconds. This inspired an optimization in ChromeOS to cache the upper half between calls, moving 3 reads to 2. ...but we can do better! Having a 32-bit timer that flips every 178 seconds is more than sufficient for Linux. Let's just use the lower half of the MCT. Times on 5420 to do 1000000 gettimeofday() calls from userspace: * Original code: 1323852 us * ChromeOS cache upper half: 1173084 us * ChromeOS + ldmia to optimize: 1045674 us * Use lower 32-bit only (this code): 1014429 us As you can see, the time used doesn't increase linearly with the number of reads and we can make 64-bit work almost as fast as 32-bit with a bit of assembly code. But since there's no real gain for 64-bit, let's go with the simplest and fastest implementation. Note: with this change roughly half the time for gettimeofday() is spent in exynos_frc_read(). The rest is timer / system call overhead. Also note: this patch disables the use of the MCT on ARM64 systems until we've sorted out how to make "cycles_t" always 32-bit. Really ARM64 systems should be using arch timers anyway. Signed-off-by: Doug Anderson <dianders@chromium.org> Acked-by Vincent Guittot <vincent.guittot@linaro.org> Signed-off-by: Kukjin Kim <kgene.kim@samsung.com> Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
2014-07-05 06:43:26 +09:00
clocksource: CMT, MTU2, TMU and STI should depend on GENERIC_CLOCKEVENTS If GENERIC_CLOCKEVENTS=n: drivers/clocksource/sh_cmt.c:54:28: error: field 'ced' has incomplete type drivers/clocksource/sh_cmt.c: In function 'sh_cmt_interrupt': drivers/clocksource/sh_cmt.c:407:23: error: 'CLOCK_EVT_MODE_ONESHOT' undeclared (first use in this function) drivers/clocksource/sh_mtu2.c:44:28: error: field 'ced' has incomplete type drivers/clocksource/sh_mtu2.c: In function 'ced_to_sh_mtu2': drivers/clocksource/sh_mtu2.c:184:70: warning: initialization from incompatible pointer type [enabled by default] drivers/clocksource/sh_mtu2.c: At top level: drivers/clocksource/sh_mtu2.c:188:16: warning: 'enum clock_event_mode' declared inside parameter list [enabled by default] drivers/clocksource/sh_tmu.c:45:28: error: field 'ced' has incomplete type drivers/clocksource/sh_tmu.c: In function 'sh_tmu_interrupt': drivers/clocksource/sh_tmu.c:207:21: error: 'CLOCK_EVT_MODE_ONESHOT' undeclared (first use in this function) drivers/clocksource/em_sti.c:44:28: error: field 'ced' has incomplete type drivers/clocksource/em_sti.c: In function 'ced_to_em_sti': drivers/clocksource/em_sti.c:251:69: warning: initialization from incompatible pointer type [enabled by default] drivers/clocksource/em_sti.c: At top level: drivers/clocksource/em_sti.c:255:16: warning: 'enum clock_event_mode' declared inside parameter list [enabled by default] Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be> Cc: Magnus Damm <damm@opensource.se> Cc: Daniel Lezcano <daniel.lezcano@linaro.org> Link: http://lkml.kernel.org/r/1395324352-9146-1-git-send-email-geert@linux-m68k.org Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2014-03-20 15:05:50 +01:00
clocksource: CMT, MTU2, TMU and STI should depend on GENERIC_CLOCKEVENTS If GENERIC_CLOCKEVENTS=n: drivers/clocksource/sh_cmt.c:54:28: error: field 'ced' has incomplete type drivers/clocksource/sh_cmt.c: In function 'sh_cmt_interrupt': drivers/clocksource/sh_cmt.c:407:23: error: 'CLOCK_EVT_MODE_ONESHOT' undeclared (first use in this function) drivers/clocksource/sh_mtu2.c:44:28: error: field 'ced' has incomplete type drivers/clocksource/sh_mtu2.c: In function 'ced_to_sh_mtu2': drivers/clocksource/sh_mtu2.c:184:70: warning: initialization from incompatible pointer type [enabled by default] drivers/clocksource/sh_mtu2.c: At top level: drivers/clocksource/sh_mtu2.c:188:16: warning: 'enum clock_event_mode' declared inside parameter list [enabled by default] drivers/clocksource/sh_tmu.c:45:28: error: field 'ced' has incomplete type drivers/clocksource/sh_tmu.c: In function 'sh_tmu_interrupt': drivers/clocksource/sh_tmu.c:207:21: error: 'CLOCK_EVT_MODE_ONESHOT' undeclared (first use in this function) drivers/clocksource/em_sti.c:44:28: error: field 'ced' has incomplete type drivers/clocksource/em_sti.c: In function 'ced_to_em_sti': drivers/clocksource/em_sti.c:251:69: warning: initialization from incompatible pointer type [enabled by default] drivers/clocksource/em_sti.c: At top level: drivers/clocksource/em_sti.c:255:16: warning: 'enum clock_event_mode' declared inside parameter list [enabled by default] Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be> Cc: Magnus Damm <damm@opensource.se> Cc: Daniel Lezcano <daniel.lezcano@linaro.org> Link: http://lkml.kernel.org/r/1395324352-9146-1-git-send-email-geert@linux-m68k.org Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2014-03-20 15:05:50 +01:00
clocksource: CMT, MTU2, TMU and STI should depend on GENERIC_CLOCKEVENTS If GENERIC_CLOCKEVENTS=n: drivers/clocksource/sh_cmt.c:54:28: error: field 'ced' has incomplete type drivers/clocksource/sh_cmt.c: In function 'sh_cmt_interrupt': drivers/clocksource/sh_cmt.c:407:23: error: 'CLOCK_EVT_MODE_ONESHOT' undeclared (first use in this function) drivers/clocksource/sh_mtu2.c:44:28: error: field 'ced' has incomplete type drivers/clocksource/sh_mtu2.c: In function 'ced_to_sh_mtu2': drivers/clocksource/sh_mtu2.c:184:70: warning: initialization from incompatible pointer type [enabled by default] drivers/clocksource/sh_mtu2.c: At top level: drivers/clocksource/sh_mtu2.c:188:16: warning: 'enum clock_event_mode' declared inside parameter list [enabled by default] drivers/clocksource/sh_tmu.c:45:28: error: field 'ced' has incomplete type drivers/clocksource/sh_tmu.c: In function 'sh_tmu_interrupt': drivers/clocksource/sh_tmu.c:207:21: error: 'CLOCK_EVT_MODE_ONESHOT' undeclared (first use in this function) drivers/clocksource/em_sti.c:44:28: error: field 'ced' has incomplete type drivers/clocksource/em_sti.c: In function 'ced_to_em_sti': drivers/clocksource/em_sti.c:251:69: warning: initialization from incompatible pointer type [enabled by default] drivers/clocksource/em_sti.c: At top level: drivers/clocksource/em_sti.c:255:16: warning: 'enum clock_event_mode' declared inside parameter list [enabled by default] Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be> Cc: Magnus Damm <damm@opensource.se> Cc: Daniel Lezcano <daniel.lezcano@linaro.org> Link: http://lkml.kernel.org/r/1395324352-9146-1-git-send-email-geert@linux-m68k.org Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2014-03-20 15:05:50 +01:00
ARM: SoC: cleanups for 3.15 These cleanup patches are mainly move stuff around and should all be harmless. They are mainly split out so that other branches can be based on top to avoid conflicts. Notable changes are: * We finally remove all mach/timex.h, after CLOCK_TICK_RATE is no longer used. (Uwe Kleine-König) * The Qualcomm MSM platform is split out into legacy mach-msm and new-style mach-qcom, to allow easier maintainance of the new hardware support without regressions. (Kumar Gala) * A rework of some of the Kconfig logic to simplify multiplatform support (Rob Herring) * Samsung Exynos gets closer to supporting multiplatform (Sachin Kamat and others) * mach-bcm3528 gets merged into mach-bcm (Stephen Warren) * at91 gains some common clock framework support (Alexandre Belloni, Jean-Jacques Hiblot and other French people). -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.12 (GNU/Linux) iQIVAwUAUz/yOWCrR//JCVInAQLOPBAAwTMkMrD8S8ggz6vfiQHZNdRPAC7NUJ46 +eYKmBVi5d6EdnjNuRElWENsh0ZosSAUFHrXsIC2NdH9sAJ9HOqWNNLymuA59Jo9 HZ/Ze6xQXDPNV7TROPoXuIli/2OCOXyyQHJsfI7h9V3PCx31qo0B5OdCxU0mtXK6 r1giREhnJFwfQMF/FTdnzhalFJoSjWwv/nkpNmQDJKRLKj9GzwQqItqw68gV6RzU Gnt6YK+9xC1B0cfWTFhAm6kbr9i7mvHoMG5tE3no2uuJMn4K7TgeMqOyvPWhmUeB EZi656szT1m5VfRWOqG+7coZO2VM4GO4NI0Xfin3GHllugOYls1il/FAfCPMLiwh RvuOmQGCkLIpdkuHop5QaI/h1EzlHA59nzTjmGf1+wWPsm0CIg08XOD9izQbRnN9 EmRqn1/8POIi17xcWyeMp8LB0APsTI+IflZFaYprEY9VlLLA/Pd+7udULhs8Bq8y 1l6fB6aPZKnDKCBy/PEIR+y+EHFEbwfrx6zm/pxVDX6P5DlQMFWL78pdBoJUa2h8 3pm/bSzNU5OSz1nJMLJv2jBTtnM5BvFgQBUi2qJ9Lr+nUhJXKCJ80kE/nOlXoCIU J952p3OhkYTQQcjuUVQeTXvRUOGB7mKok0pDFZNE6c7faqxTCudMABQq/KbMFstU eE3cH5FyYj4= =GcBb -----END PGP SIGNATURE----- Merge tag 'cleanup-3.15' of git://git.kernel.org/pub/scm/linux/kernel/git/arm/arm-soc Pull ARM SoC cleanups from Arnd Bergmann: "These cleanup patches are mainly move stuff around and should all be harmless. They are mainly split out so that other branches can be based on top to avoid conflicts. Notable changes are: - We finally remove all mach/timex.h, after CLOCK_TICK_RATE is no longer used (Uwe Kleine-König) - The Qualcomm MSM platform is split out into legacy mach-msm and new-style mach-qcom, to allow easier maintainance of the new hardware support without regressions (Kumar Gala) - A rework of some of the Kconfig logic to simplify multiplatform support (Rob Herring) - Samsung Exynos gets closer to supporting multiplatform (Sachin Kamat and others) - mach-bcm3528 gets merged into mach-bcm (Stephen Warren) - at91 gains some common clock framework support (Alexandre Belloni, Jean-Jacques Hiblot and other French people)" * tag 'cleanup-3.15' of git://git.kernel.org/pub/scm/linux/kernel/git/arm/arm-soc: (89 commits) ARM: hisi: select HAVE_ARM_SCU only for SMP ARM: efm32: allow uncompress debug output ARM: prima2: build reset code standalone ARM: at91: add PWM clock ARM: at91: move sam9261 SoC to common clk ARM: at91: prepare common clk transition for sam9261 SoC ARM: at91: updated the at91_dt_defconfig with support for the ADS7846 ARM: at91: dt: sam9261: Device Tree support for the at91sam9261ek ARM: at91: dt: defconfig: Added the sam9261 to the list of DT-enabled SOCs ARM: at91: dt: Add at91sam9261 dt SoC support ARM: at91: switch sam9rl to common clock framework ARM: at91/dt: define main clk frequency of at91sam9rlek ARM: at91/dt: define at91sam9rl clocks ARM: at91: prepare common clk transition for sam9rl SoCs ARM: at91: prepare sam9 dt boards transition to common clk ARM: at91: dt: sam9rl: Device Tree for the at91sam9rlek ARM: at91/defconfig: Add the sam9rl to the list of DT-enabled SOCs ARM: at91: Add at91sam9rl DT SoC support ARM: at91: prepare at91sam9rl DT transition ARM: at91/defconfig: refresh at91sam9260_9g20_defconfig ...
2014-04-05 13:51:19 -07:00