linaro-kernel

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10094 discussions

[ACTIVITY] (Arnd Bergmann) 2012-03-03 - 2012-03-09

by Arnd Bergmann

== Arnd Bergmann <arnd> == === Highlights === * Merged tons of patches into the arm-soc tree, then handed over to Olof for the meantime but will probably take over again for the merge window * Sent out status of the arm-soc tree report for the 3.4 merge window * Worked with Jason Cooper to get Kirkwood DT conversion started * Worked with Roland Stigge to get him established as lpc32xx maintainer and get his code for that platform in, he will work on lpc32xx DT stuff in the v3.5 cycle. * Worked with Alan Ott and Mathieu Poirier to start getting my randconfig patches merged. * Worked with Niklas Hernaeus and Lee Jones to speed up the ux500 DT conversion. * Code review: pxa/mmp DT patches, bmp085 driver, at91, dreamplug, ... === Plans === * Keep watching over various DT conversions * Dig out my old series for inb/outb elimination and get that into shape for -next after the merge window

13 years, 1 month

[ACTIVITY] (Linus Walleij) 2012-03-03 - 2012-03-09

by Linus Walleij

== Linus Walleij linusw == === Highlights === * Merged pin control patches from Stephen Warren, finalizing the API transition. * Sent a patch series converting U300 over to using pin control. * Updated pinctrl blueprints, created work for myself by opening a ux500 pinctrl transition blueprint. * Sent some AB8500 updates including AB8505 support to Sam for MFD. * Looking over some other internal patches, particularly patches touching the core kernel outside our own drivers, posting a cpufreq-ondemand patch today. * Discussed dmaengine. * Discussed internal alignment of Linaro activities for two issues as requested by Andrea. === Plans === * Test the U9540 patches on real hardware and rework as outlined by Arnd. * Accumulate pinctrl patches for kernel v3.4 merge window. * Work on the blueprint for ux500 pinctrl. * Test the PL08x patches on the Ericsson Research PB11MPCore and submit platform data for using pl08x DMA on that platform. * Look into other Ux500 stuff in need of mainlining... like - Ux500 clocks - the HWMON stuff. === Issues === * None! Thanks, Linus Walleij

13 years, 1 month

[RFC] Scheduler recorder and playback

by Pantelis Antoniou

Hi there, There's considerable activity in the subject of the scheduler lately and how to adapt it to the peculiarities of the new class of hardware coming out lately, like the big.LITTLE class of devices from a number of manufacturers. The platforms that Linux runs are very diverse, and run differing workloads. For example most consumer devices will very likely run something like Android, with common use cases such as audio and/or video playback. Methods to achieve lower power consumption using a power aware scheduler are under investigation. Similarly for server applications, or VM hosting, the behavior of the scheduler shouldn't have adverse performance implications; any power saving on top of that would be a welcome improvement. The current issue is that scheduler development is not easily shared between developers. Each developer has their own 'itch', be it Android use cases, server workloads, VM, etc. The risk is high of optimizing for one's own use case and causing severe degradation on most other use cases. One way to fix this problem would be the development of a method with which one could perform a given use-case workload in a host, record the activity in a interchangeable portable trace format file, and then play it back on another host via a playback application that will generate an approximately similar load which was observed during recording. The way that the two hosts respond under the same load generated by the playback application can be compared, so that the performance of the two scheduler implementations measured in various metrics (like performance, power consumption etc.) can be evaluated. The fidelity of the this approximation is of great importance but it is debatable if it is possible to have a fully identical load generated, since details of the hosts might differ in such a way that such a thing is impossible. I believe that it should be possible at least to simulate a purely CPU load, and the blocking behavior of tasks, in such a way that it would result in scheduler decisions that can be compared and shared among developers. The recording part I believe can be handled by the kernel's tracing infrastructure, either by using the existing tracepoints, or need be adding more; possibly even creating a new tracer solely for this purpose. Since some applications can adapt their behavior according to insufficient system resources (think media players that can drop frames for example), I think it would be beneficial to record such events to the same trace file. The trace file should have a portable format so that it can be freely shared between developers. An ASCII format like we currently use should be OK, as long as it doesn't cause too much of an effect during execution of the recording. The playback application can be implemented via two ways. One way, which is the LinSched way would be to have the full scheduler implementation compiled as part of said application, and use application specific methods to evaluate performance. While this will work, it won't allow comparison of the two hosts in a meaningful manner. For both scheduler and platform evaluation, the playback application will generate the load on the running host by simulating the source host's recorded work load session. That means emulating process activity like forks, thread spawning, blocking on resources etc. It is not clear to me yet if that's possible without using some kind of kernel level helper module, but not requiring such is desirable. Since one would have the full trace of scheduling activity: past, present and future; there would be the possibility of generating a perfect schedule (as defined by best performance, or best power consumption), and use it as a yardstick of evaluation against the actual scheduler. Comparing the results, you would get an estimate of the best case improvement that could be achieved if the ideal scheduler existed. I know this is a bit long, but I hope this can be a basis of thinking on how to go about developing this. Regards -- Pantelis

13 years, 1 month

[ACTIVITY] (Anton Vorontsov) 2012-02-27 - 2012-03-02

by Anton Vorontsov

== Highlights == * Debugged cgroups inaccuracy when calculating memory usage, prepared a hack that fixes the issue, sent an RFC. A proper fix needs to be implemented though; * Reviewing/comparing various low memory notifications: the one from Minchan Kim (http://lwn.net/Articles/475791/), Nokia's memory meter (http://lkml.org/lkml/2012/1/4/208) and vmevent (http://lkml.org/lkml/2012/1/17/370). Feature and reception-wise VM event framework looks like a winner; * Tried vmevents notifications framework, prepared a few fixes; * Added two-way notifications to vmevents; * Added vmevents support for the ulmkd. -- Anton Vorontsov Email: cbouatmailru(a)gmail.com

13 years, 1 month

What is bug of OMAP4460 that make oprofile can not run normally

by Kyler Zhang

Hi all, We are know that the OMAP4460's PMU is buggy, which loses PMU interrupt always. But I do not know what the real bug is, the HW bug or Software bug? What the bug is? Could some one give a point? Kyler Zhang

13 years, 1 month

[ACTIVITY] (Deepak Saxena) Feb 26 - Mar 3

by Deepak Saxena

== Deepak Saxena <dsaxena> == === Highlights === * Lots of catching up on emails from pre-ELC * 1-on-1's * Discussions on kernel upstreaming and roadmap process * Review of big.LITTLE Task Migration test plan === Plans === * Work on kernel wiki page updates * 1-on-1's, sub-team meetings * Working on roadmap cards * Start outline of porting guide that was discussed @ Connect * Continue looking at kernel upstreaming and roadmap process * Start outline of member's update on how kernel development process differs from traditional software development. * Dive deeper into big.LITTLE switcher project === Issues === *** I have lost all wiki access permissions (can't edit or create pages, *** *** can't acces /Internal). RT ticket filed last week but no progress. *** === Travel/Time Off === * Taking Monday March 12th mostly off, might be online parts of the day * Possible off May 4-10th. * Connect Q2

13 years, 1 month

re: What is bug of OMAP4460 that make oprofile can not run normally

by David Long

>Hi all, >We are know that the OMAP4460's PMU is buggy, which loses PMU interrupt always. >But I do not know what the real bug is, the HW bug or Software bug? >What the bug is? Kyler, This is a hardware problem in the ARM core. It is not specific to the 4460, for instance it also occurs in the 4430 (and presumably non-TI SoCs). The result of this bug is that PMU counter overflow interrupts are sometimes lost. The affect can be reduced by paralleling PMU counters, but this only reduces the problem statistically somewhat. There is no complete workaround. The problem is described in ARM errata, but I do not believe that information is generally available. I think it can be found on a Freescale site though. I suggest googling for ARM errata 628216. I believe this will be fixed in a future iteration of the design, but I do not know when this will be released. -dl David Long Linaro

13 years, 1 month

[ACTIVITY] (Shawn Guo) Week of Feb 27

by Shawn Guo

=== Device Tree === * Sent the full series (20 patches) adding DT support for IMX audio. - Covert audmux driver to a platform driver and move it into ASoC - Consolidate PowerPC SSI driver and make it work for IMX - Add imx-sgtl5000 machine driver (DT only) === Misc === * Reviewed ANATOP MFD and Regulator series (v7) from Paul Liu -- Regards, Shawn

13 years, 1 month

[Activity] (Niklas Hernaeus) 2012-02-27 - 2012-03-02

by Niklas Hernaeus

== Niklas Hernaeus <nhe> == === General activity === * Made the initial DT system to build and boot reliably. * Sent out a patch for this initial DT system. /nhe

13 years, 1 month

[PATCH 3/3] vmevent: Should not grab mutex in the atomic context

by Anton Vorontsov

There is not need to grab mutex in the atomic context, moreover this is wrong and causes the following bug: BUG: sleeping function called from invalid context at kernel/mutex.c:271 in_atomic(): 1, irqs_disabled(): 1, pid: 1056, name: m no locks held by m/1056. irq event stamp: 58768 hardirqs last enabled at (58767): [<ffffffff8101ca35>] do_page_fault+0x275/0x450 hardirqs last disabled at (58768): [<ffffffff81325a2b>] apic_timer_interrupt+0x6b/0x80 softirqs last enabled at (58676): [<ffffffff81038def>] __do_softirq+0x10f/0x160 softirqs last disabled at (58671): [<ffffffff813262ac>] call_softirq+0x1c/0x26 Pid: 1056, comm: m Not tainted 3.2.0+ #3 Call Trace: <IRQ> [<ffffffff81062530>] ? print_irqtrace_events+0xd0/0xe0 [<ffffffff8102f5da>] __might_sleep+0x12a/0x1e0 [<ffffffff81321dbc>] mutex_lock_nested+0x3c/0x340 [<ffffffff81053a8c>] ? __run_hrtimer+0x4c/0x100 [<ffffffff810bd920>] ? vmevent_read+0x100/0x100 [<ffffffff810bd79e>] vmevent_sample+0x6e/0xf0 [<ffffffff810bd946>] vmevent_timer_fn+0x26/0x60 [<ffffffff81053a92>] __run_hrtimer+0x52/0x100 [<ffffffff81054463>] hrtimer_interrupt+0xf3/0x220 [<ffffffff810166d4>] smp_apic_timer_interrupt+0x64/0xa0 [<ffffffff81325a30>] apic_timer_interrupt+0x70/0x80 <EOI> [<ffffffff8101ca3a>] ? do_page_fault+0x27a/0x450 [<ffffffff8101ca35>] ? do_page_fault+0x275/0x450 [<ffffffff810036bf>] ? do_softirq+0x6f/0xc0 [<ffffffff8132485d>] ? retint_restore_args+0xe/0xe [<ffffffff8132484a>] ? retint_swapgs+0xe/0x13 [<ffffffff8116b31d>] ? trace_hardirqs_off_thunk+0x3a/0x3c [<ffffffff81324a3f>] page_fault+0x1f/0x30 Signed-off-by: Anton Vorontsov <anton.vorontsov(a)linaro.org> --- The patch is for git://github.com/penberg/linux.git vmevent/core. mm/vmevent.c | 4 ---- 1 files changed, 0 insertions(+), 4 deletions(-) diff --git a/mm/vmevent.c b/mm/vmevent.c index 1375f9d..1dbefb5 100644 --- a/mm/vmevent.c +++ b/mm/vmevent.c @@ -71,8 +71,6 @@ static void vmevent_sample(struct vmevent_watch *watch) if (!vmevent_match(watch, &event)) return; - mutex_lock(&watch->mutex); - watch->pending = true; if (watch->config.event_attrs & VMEVENT_EATTR_NR_AVAIL_PAGES) @@ -85,8 +83,6 @@ static void vmevent_sample(struct vmevent_watch *watch) watch->attr_values[n++] = event.nr_swap_pages; watch->nr_attrs = n; - - mutex_unlock(&watch->mutex); } static enum hrtimer_restart vmevent_timer_fn(struct hrtimer *hrtimer) -- 1.7.7.6

13 years, 1 month

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