From mboxrd@z Thu Jan 1 00:00:00 1970 From: Hao Xu Subject: Re: [PATCH for-5.15 v2] io_uring: consider cgroup setting when binding sqpoll cpu Date: Sat, 28 Aug 2021 01:03:59 +0800 Message-ID: References: <20210827141315.235974-1-haoxu@linux.alibaba.com> <0988b0dc-232f-80cd-c984-2364c0dee69f@kernel.dk> <592ba01a-a128-f781-d920-2b480f91c451@linux.alibaba.com> Mime-Version: 1.0 Content-Transfer-Encoding: 8bit Return-path: In-Reply-To: <592ba01a-a128-f781-d920-2b480f91c451-KPsoFbNs7GizrGE5bRqYAgC/G2K4zDHf@public.gmane.org> List-ID: Content-Type: text/plain; charset="utf-8"; format="flowed" To: Jens Axboe , Zefan Li , Tejun Heo , Johannes Weiner , Pavel Begunkov Cc: io-uring-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Joseph Qi 在 2021/8/28 上午12:57, Hao Xu 写道: > 在 2021/8/27 下午10:18, Jens Axboe 写道: >> On 8/27/21 8:13 AM, Hao Xu wrote: >>> Since sqthread is userspace like thread now, it should respect cgroup >>> setting, thus we should consider current allowed cpuset when doing >>> cpu binding for sqthread. >> >> In general, this looks way better than v1. Just a few minor comments >> below. >> >>> @@ -7000,6 +7001,16 @@ static bool io_sqd_handle_event(struct >>> io_sq_data *sqd) >>>       return did_sig || test_bit(IO_SQ_THREAD_SHOULD_STOP, &sqd->state); >>>   } >>> +static int io_sq_bind_cpu(int cpu) >>> +{ >>> +    if (!test_cpu_in_current_cpuset(cpu)) >>> +        pr_warn("sqthread %d: bound cpu not allowed\n", current->pid); >>> +    else >>> +        set_cpus_allowed_ptr(current, cpumask_of(cpu)); >>> + >>> +    return 0; >>> +} >> >> This should not be triggerable, unless the set changes between creation >> and the thread being created. Hence maybe the warn is fine. I'd probably >> prefer terminating the thread at that point, which would result in an >> -EOWNERDEAD return when someone attempts to wake the thread. >> >> Which is probably OK, as we really should not hit this path. > Actually I think cpuset change offen happen in container environment( > at leaset in my practice), eg. by resource monitor and balancer. So I > did this check to make sure we are still maintain sq_cpu logic at that > time as possible as we can. Though the problem is still there during > sqthread running time(the cpuset can change at anytime, which changes > the cpumask of sqthread) And because the cpumask of sqthread may be changed by the cgroup cpuset change at any time, so here I just print a warnning rather than terminating sqthread due to this 'normal thing'.. > > Regards, > Hao >> >>> diff --git a/include/linux/cpuset.h b/include/linux/cpuset.h >>> index 04c20de66afc..fad77c91bc1f 100644 >>> --- a/include/linux/cpuset.h >>> +++ b/include/linux/cpuset.h >>> @@ -116,6 +116,8 @@ static inline int cpuset_do_slab_mem_spread(void) >>>   extern bool current_cpuset_is_being_rebound(void); >>> +extern bool test_cpu_in_current_cpuset(int cpu); >>> + >>>   extern void rebuild_sched_domains(void); >>>   extern void cpuset_print_current_mems_allowed(void); >>> @@ -257,6 +259,11 @@ static inline bool >>> current_cpuset_is_being_rebound(void) >>>       return false; >>>   } >>> +static inline bool test_cpu_in_current_cpuset(int cpu) >>> +{ >>> +    return false; >>> +} >>> + >>>   static inline void rebuild_sched_domains(void) >>>   { >>>       partition_sched_domains(1, NULL, NULL); >>> diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c >>> index adb5190c4429..a63c27e9430e 100644 >>> --- a/kernel/cgroup/cpuset.c >>> +++ b/kernel/cgroup/cpuset.c >>> @@ -1849,6 +1849,17 @@ bool current_cpuset_is_being_rebound(void) >>>       return ret; >>>   } >>> +bool test_cpu_in_current_cpuset(int cpu) >>> +{ >>> +    bool ret; >>> + >>> +    rcu_read_lock(); >>> +    ret = cpumask_test_cpu(cpu, task_cs(current)->effective_cpus); >>> +    rcu_read_unlock(); >>> + >>> +    return ret; >>> +} >>> + >>>   static int update_relax_domain_level(struct cpuset *cs, s64 val) >>>   { >>>   #ifdef CONFIG_SMP >> >> In terms of review and so forth, I'd split this into a prep patch. Then >> patch 2 just becomes the io_uring consumer of it. >>