user/sven/linux.git/kernel/smp.c, branch v5.9.5

smp: Fix a potential usage of stale nr_cpus

2020-07-22T08:22:04Z

The get_option() maybe return 0, it means that the nr_cpus is not initialized. Then we will use the stale nr_cpus to initialize the nr_cpu_ids. So fix it. Signed-off-by: Muchun Song Signed-off-by: Peter Zijlstra (Intel) Link: https://lkml.kernel.org/r/20200716070457.53255-1-songmuchun@bytedance.com

smp, irq_work: Continue smp_call_function() and irq_work() integration

2020-06-28T15:01:20Z

Instead of relying on BUG_ON() to ensure the various data structures line up, use a bunch of horrible unions to make it all automatic. Much of the union magic is to ensure irq_work and smp_call_function do not (yet) see the members of their respective data structures change name. Suggested-by: Linus Torvalds Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Ingo Molnar Reviewed-by: Frederic Weisbecker Link: https://lkml.kernel.org/r/20200622100825.844455025@infradead.org

Merge tag 'sched-core-2020-06-02' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2020-06-03T20:06:42Z

Pull scheduler updates from Ingo Molnar: "The changes in this cycle are: - Optimize the task wakeup CPU selection logic, to improve scalability and reduce wakeup latency spikes - PELT enhancements - CFS bandwidth handling fixes - Optimize the wakeup path by remove rq->wake_list and replacing it with ->ttwu_pending - Optimize IPI cross-calls by making flush_smp_call_function_queue() process sync callbacks first. - Misc fixes and enhancements" * tag 'sched-core-2020-06-02' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (36 commits) irq_work: Define irq_work_single() on !CONFIG_IRQ_WORK too sched/headers: Split out open-coded prototypes into kernel/sched/smp.h sched: Replace rq::wake_list sched: Add rq::ttwu_pending irq_work, smp: Allow irq_work on call_single_queue smp: Optimize send_call_function_single_ipi() smp: Move irq_work_run() out of flush_smp_call_function_queue() smp: Optimize flush_smp_call_function_queue() sched: Fix smp_call_function_single_async() usage for ILB sched/core: Offload wakee task activation if it the wakee is descheduling sched/core: Optimize ttwu() spinning on p->on_cpu sched: Defend cfs and rt bandwidth quota against overflow sched/cpuacct: Fix charge cpuacct.usage_sys sched/fair: Replace zero-length array with flexible-array sched/pelt: Sync util/runnable_sum with PELT window when propagating sched/cpuacct: Use __this_cpu_add() instead of this_cpu_ptr() sched/fair: Optimize enqueue_task_fair() sched: Make scheduler_ipi inline sched: Clean up scheduler_ipi() sched/core: Simplify sched_init() ...

irq_work: Define irq_work_single() on !CONFIG_IRQ_WORK too

2020-06-02T10:34:45Z

Some SMP platforms don't have CONFIG_IRQ_WORK defined, resulting in a link error at build time. Define a stub and clean up the prototype definitions. Reported-by: kbuild test robot Signed-off-by: Ingo Molnar Acked-by: Peter Zijlstra Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar

sched/headers: Split out open-coded prototypes into kernel/sched/smp.h

2020-05-28T09:03:20Z

Move the prototypes for sched_ttwu_pending() and send_call_function_single_ipi() into the newly created kernel/sched/smp.h header, to make sure they are all the same, and to architectures happy that use -Wmissing-prototypes. Signed-off-by: Ingo Molnar

sched: Replace rq::wake_list

2020-05-28T08:54:16Z

The recent commit: 90b5363acd47 ("sched: Clean up scheduler_ipi()") got smp_call_function_single_async() subtly wrong. Even though it will return -EBUSY when trying to re-use a csd, that condition is not atomic and still requires external serialization. The change in ttwu_queue_remote() got this wrong. While on first reading ttwu_queue_remote() has an atomic test-and-set that appears to serialize the use, the matching 'release' is not in the right place to actually guarantee this serialization. The actual race is vs the sched_ttwu_pending() call in the idle loop; that can run the wakeup-list without consuming the CSD. Instead of trying to chain the lists, merge them. Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Ingo Molnar Link: https://lore.kernel.org/r/20200526161908.129371594@infradead.org

irq_work, smp: Allow irq_work on call_single_queue

2020-05-28T08:54:15Z

Currently irq_work_queue_on() will issue an unconditional arch_send_call_function_single_ipi() and has the handler do irq_work_run(). This is unfortunate in that it makes the IPI handler look at a second cacheline and it misses the opportunity to avoid the IPI. Instead note that struct irq_work and struct __call_single_data are very similar in layout, so use a few bits in the flags word to encode a type and stick the irq_work on the call_single_queue list. Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Ingo Molnar Link: https://lore.kernel.org/r/20200526161908.011635912@infradead.org

smp: Optimize send_call_function_single_ipi()

2020-05-28T08:54:15Z

Just like the ttwu_queue_remote() IPI, make use of _TIF_POLLING_NRFLAG to avoid sending IPIs to idle CPUs. [ mingo: Fix UP build bug. ] Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Ingo Molnar Link: https://lore.kernel.org/r/20200526161907.953304789@infradead.org

smp: Move irq_work_run() out of flush_smp_call_function_queue()

2020-05-28T08:54:15Z

This ensures flush_smp_call_function_queue() is strictly about call_single_queue. Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Ingo Molnar Link: https://lore.kernel.org/r/20200526161907.895109676@infradead.org

smp: Optimize flush_smp_call_function_queue()

2020-05-28T08:54:15Z

The call_single_queue can contain (two) different callbacks, synchronous and asynchronous. The current interrupt handler runs them in-order, which means that remote CPUs that are waiting for their synchronous call can be delayed by running asynchronous callbacks. Rework the interrupt handler to first run the synchonous callbacks. Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Ingo Molnar Link: https://lore.kernel.org/r/20200526161907.836818381@infradead.org

user/sven/linux.git/kernel/smp.c, branch v5.9.5

smp: Fix a potential usage of stale nr_cpus

smp, irq_work: Continue smp_call_function*() and irq_work*() integration

Merge tag 'sched-core-2020-06-02' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

irq_work: Define irq_work_single() on !CONFIG_IRQ_WORK too

sched/headers: Split out open-coded prototypes into kernel/sched/smp.h

sched: Replace rq::wake_list

irq_work, smp: Allow irq_work on call_single_queue

smp: Optimize send_call_function_single_ipi()

smp: Move irq_work_run() out of flush_smp_call_function_queue()

smp: Optimize flush_smp_call_function_queue()

smp, irq_work: Continue smp_call_function() and irq_work() integration