lkml.org 
[lkml]   [2006]   [Jun]   [30]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [Patch][RFC] Disabling per-tgid stats on task exit in taskstats
Shailabh Nagar <nagar@watson.ibm.com> wrote:
>
> +/*
> + * Per-task exit data sent from the kernel to user space
> + * is tagged by an id based on grouping of cpus.
> + *
> + * If userspace specifies a non-zero P as the nl_pid field of
> + * the sockaddr_nl structure while binding to a netlink socket,
> + * it will receive exit data from threads that exited on cpus in the range
> + *
> + * [(P-1)*Y, P*Y-1]
> + *
> + * where Y = TASKSTATS_CPUS_PER_SET
> + * i.e. if TASKSTATS_CPUS_PER_SET is 16,
> + * to listen to data from cpus 0..15, specify P=1
> + * for cpus 16..32, specify P=2 etc.
> + *
> + * To listen to data from all cpus, userspace should use P=0
> + */
> +
> +#define TASKSTATS_CPUS_PER_SET 16

The constant is unpleasant.

If we're going to abuse nl_pid then how about we design things so that
nl_pid is treated as two 16-bit words - one word is the start CPU and the
other word is the end cpu?

Or, if a 65536-CPU limit is too scary, make the bottom 8 bits of nl_pid be
the number of CPUS (ie: TASKSTATS_CPUS_PER_SET) and the top 24 bits is the
starting CPU.

<avoids mentioning nl_pad>

It'd be better to use a cpumask, of course..
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2006-07-02 00:10    [W:0.726 / U:0.816 seconds]
©2003-2014 Jasper Spaans. Advertise on this site