Re: per BDI dirty limit (was Re: -mm merge plans for 2.6.24)

[Fengguang Wu <wfg@mail.ustc.edu.cn>]

On Tue, Oct 02, 2007 at 10:17:05AM +0200, Peter Zijlstra wrote:
> On Mon, 2007-10-01 at 14:22 -0700, Andrew Morton wrote:
> 
> > nfs-remove-congestion_end.patch
> > lib-percpu_counter_add.patch
> > lib-percpu_counter_sub.patch
> > lib-percpu_counter-variable-batch.patch
> > lib-make-percpu_counter_add-take-s64.patch
> > lib-percpu_counter_set.patch
> > lib-percpu_counter_sum_positive.patch
> > lib-percpu_count_sum.patch
> > lib-percpu_counter_init-error-handling.patch
> > lib-percpu_counter_init_irq.patch
> > mm-bdi-init-hooks.patch
> > mm-scalable-bdi-statistics-counters.patch
> > mm-count-reclaimable-pages-per-bdi.patch
> > mm-count-writeback-pages-per-bdi.patch
> 
> This one:
> > mm-expose-bdi-statistics-in-sysfs.patch
> 
> > lib-floating-proportions.patch
> > mm-per-device-dirty-threshold.patch
> > mm-per-device-dirty-threshold-warning-fix.patch
> > mm-per-device-dirty-threshold-fix.patch
> > mm-dirty-balancing-for-tasks.patch
> > mm-dirty-balancing-for-tasks-warning-fix.patch
> 
> And, this one:
> > debug-sysfs-files-for-the-current-ratio-size-total.patch
> 
> 
> I'm not sure polluting /sys/block/<foo>/queue/ like that is The Right
> Thing. These patches sure were handy when debugging this, but not sure
> they want to move to maineline.
 
> Maybe we want /sys/bdi/<foo>/ or maybe /debug/bdi/<foo>/

I'd vote for /sys/bdi/.

It will be more than debug variables.  It's good to expose per-bdi
tunable parameters and allow one to view bdi states.

It would also allow one to tune things like NFS readahead :-)