Messages in this thread | | | Subject | Re: [PATCH v7 1/3] trace: Make removal of ring buffer pages atomic | From | Steven Rostedt <> | Date | Tue, 08 May 2012 23:38:02 -0400 |
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On Thu, 2012-05-03 at 18:59 -0700, Vaibhav Nagarnaik wrote:
> + get_online_cpus(); > + /* > + * Fire off all the required work handlers > + * Look out for offline CPUs > + */ > + for_each_buffer_cpu(buffer, cpu) { > + cpu_buffer = buffer->buffers[cpu]; > + if (!cpu_buffer->nr_pages_to_update || > + !cpu_online(cpu)) > + continue; > + > + schedule_work_on(cpu, &cpu_buffer->update_pages_work); > + } > + /* > + * This loop is for the CPUs that are not online. > + * We can't schedule anything on them, but it's not necessary > + * since we can change their buffer sizes without any race. > + */ > + for_each_buffer_cpu(buffer, cpu) { > + cpu_buffer = buffer->buffers[cpu]; > + if (!cpu_buffer->nr_pages_to_update || > + cpu_online(cpu)) > + continue; > + > + rb_update_pages(cpu_buffer); > }
BTW, why the two loops and not just:
for_each_buffer_cpu(buffer, cpu) { cpu_buffer = buffer->buffers[cpu]; if (!cpu_buffer->nr_pages_to_update) continue;
if (cpu_online(cpu)) schedule_work_on(cpu, &cpu_buffer->update_pages_work); else rb_update_pages(cpu_buffer); }
??
> > /* wait for all the updates to complete */ > for_each_buffer_cpu(buffer, cpu) { > cpu_buffer = buffer->buffers[cpu]; > - if (cpu_buffer->nr_pages_to_update) { > - update_pages_handler(cpu_buffer); > - } > + if (!cpu_buffer->nr_pages_to_update||
!cpu_buffer->nr_pages_to_update ||
-- Steve
> + !cpu_online(cpu)) > + continue; > + > + wait_for_completion(&cpu_buffer->update_completion); > + /* reset this value */ > + cpu_buffer->nr_pages_to_update = 0; > }
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