Messages in this thread | | | Subject | Re: + mm-add-proc-controls-for-pdflush-threads.patch added to -mm tree | From | "Peter W. Morreale" <> | Date | Mon, 05 Jan 2009 23:37:38 +0000 |
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On Tue, 2009-01-06 at 02:21 +0300, Alexey Dobriyan wrote: > On Mon, Jan 05, 2009 at 02:53:03PM -0800, akpm@linux-foundation.org wrote: > > Subject: mm: add /proc controls for pdflush threads > > > @@ -1022,6 +1023,28 @@ static struct ctl_table vm_table[] = { > > .proc_handler = &proc_dointvec, > > }, > > { > > + .ctl_name = CTL_UNNUMBERED, > > + .procname = "nr_pdflush_threads_min", > > + .data = &nr_pdflush_threads_min, > > + .maxlen = sizeof nr_pdflush_threads_min, > > + .mode = 0644 /* read-write */, > > + .proc_handler = &proc_dointvec_minmax, > > + .strategy = &sysctl_intvec, > > .strategy isn't needed for /proc-only sysctls. >
It is for checking the bounds of the new setting. Without it would be possible to set the max thread count higher than the minimum and vice versa. What you would actually wind up with would depend upon the number of outstanding threads at the time of the sysctl change.
The specific limitations are that you cannot set max < min and min > max. In addition, since the only way to get another pdflush thread is via a pdflush thread, the minimum 'min' is 1. And the 'max' is an arbitrary 1000.
Best, -PWM
> > + .extra1 = &one, > > + .extra2 = &nr_pdflush_threads_max, > > + }, > > + { > > + .ctl_name = CTL_UNNUMBERED, > > + .procname = "nr_pdflush_threads_max", > > + .data = &nr_pdflush_threads_max, > > + .maxlen = sizeof nr_pdflush_threads_max, > > + .mode = 0644 /* read-write */, > > + .proc_handler = &proc_dointvec_minmax, > > + .strategy = &sysctl_intvec, > > .strategy isn't needed for /proc-only sysctls.
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