On 04/07/2016 04:41 PM, Tejun Heo wrote:
Hello, Waiman.
On Thu, Apr 07, 2016 at 04:37:06PM -0400, Waiman Long wrote:
I would say that because I am lazy, I don't want compute the deltas every
time I want to see the effect of running a certain type of workload on the
statistics counts. I have use
Hello, Waiman.
On Thu, Apr 07, 2016 at 04:37:06PM -0400, Waiman Long wrote:
> I would say that because I am lazy, I don't want compute the deltas every
> time I want to see the effect of running a certain type of workload on the
> statistics counts. I have use case that I need to track 10 or so st
On 04/07/2016 02:58 PM, Tejun Heo wrote:
Hello, Waiman.
On Thu, Apr 07, 2016 at 02:52:33PM -0400, Waiman Long wrote:
As long as atomic reset is an optional feature that caller can choose at
init time, I am OK to provide this functionality. I just don't want it to be
the default because of the p
On 04/07/2016 12:06 PM, Tejun Heo wrote:
Hello, Waiman.
On Thu, Apr 07, 2016 at 11:58:13AM -0400, Waiman Long wrote:
We can certainly make it watertight. However, that will certainly require
adding performance overhead in the percpu stats update fast path which I am
not willing to pay.
There a
Hello, Waiman.
On Thu, Apr 07, 2016 at 02:52:33PM -0400, Waiman Long wrote:
> As long as atomic reset is an optional feature that caller can choose at
> init time, I am OK to provide this functionality. I just don't want it to be
> the default because of the performance overhead.
Please take a lo
Hello, Waiman.
On Thu, Apr 07, 2016 at 11:58:13AM -0400, Waiman Long wrote:
> We can certainly make it watertight. However, that will certainly require
> adding performance overhead in the percpu stats update fast path which I am
> not willing to pay.
There are multiple options depending on the s
On 04/06/2016 06:54 PM, Tejun Heo wrote:
Hello,
On Wed, Apr 06, 2016 at 05:51:45PM -0400, Waiman Long wrote:
+ /*
+* If a statistics count is in the middle of being updated, it
+* is possible that the above clearing may not work. So we need
+* to double check again
Hello,
On Wed, Apr 06, 2016 at 05:51:45PM -0400, Waiman Long wrote:
> >>+ /*
> >>+* If a statistics count is in the middle of being updated, it
> >>+* is possible that the above clearing may not work. So we need
> >>+* to double check again to make sure that the counters are really
>
On 04/04/2016 03:09 PM, Christoph Lameter wrote:
On Mon, 4 Apr 2016, Waiman Long wrote:
+ if ((unsigned int)stat>= pcs->nstats)
+ return;
+ preempt_disable();
+ pstat = this_cpu_ptr(&pcs->stats[stat]);
+ *pstat += cnt;
+ preempt_enable();
+}
pstat =
On 04/04/2016 12:02 PM, Tejun Heo wrote:
Hello,
On Fri, Apr 01, 2016 at 11:09:37PM -0400, Waiman Long wrote:
...
+struct percpu_stats {
+ unsigned long __percpu *stats;
I'm not sure ulong is the best choice here. Atomic reads on 32bit are
nice but people often need 64bit counters for st
On 04/04/2016 12:02 PM, Tejun Heo wrote:
Hello,
On Fri, Apr 01, 2016 at 11:09:37PM -0400, Waiman Long wrote:
...
+struct percpu_stats {
+ unsigned long __percpu *stats;
I'm not sure ulong is the best choice here. Atomic reads on 32bit are
nice but people often need 64bit counters for st
On Mon, 4 Apr 2016, Waiman Long wrote:
> > > + if ((unsigned int)stat>= pcs->nstats)
> > > + return;
> > > + preempt_disable();
> > > + pstat = this_cpu_ptr(&pcs->stats[stat]);
> > > + *pstat += cnt;
> > > + preempt_enable();
> > > +}
> > pstat = get_cpu_ptr(&pcs->stats[stat]);
> > *pstat
On 04/04/2016 03:36 AM, Nikolay Borisov wrote:
On 04/02/2016 06:09 AM, Waiman Long wrote:
This patch introduces a set of simple per-cpu statictics count helper
functions that can be used by other kernel subsystems for keeping
track of the number of events that happens. It is per-cpu based to
re
Hello,
On Fri, Apr 01, 2016 at 11:09:37PM -0400, Waiman Long wrote:
...
> +struct percpu_stats {
> + unsigned long __percpu *stats;
I'm not sure ulong is the best choice here. Atomic reads on 32bit are
nice but people often need 64bit counters for stats. It probably is a
better idea to use
On 04/02/2016 06:09 AM, Waiman Long wrote:
> This patch introduces a set of simple per-cpu statictics count helper
> functions that can be used by other kernel subsystems for keeping
> track of the number of events that happens. It is per-cpu based to
> reduce overhead and improve accuracy of the
This patch introduces a set of simple per-cpu statictics count helper
functions that can be used by other kernel subsystems for keeping
track of the number of events that happens. It is per-cpu based to
reduce overhead and improve accuracy of the counter. Using per-cpu
counter is usually overkill f
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