On Tue, Nov 9, 2010 at 6:24 PM, Greg Thelen <gthelen@xxxxxxxxxx> wrote:
> If called with a mem_cgroup, then throttle_vm_writeout() should
> query the given cgroup for its dirty memory usage limits.
>
> dirty_writeback_pages() is no longer used, so delete it.
>
> Signed-off-by: Greg Thelen <gthelen@xxxxxxxxxx>
Reviewed-by: Minchan Kim <minchan.kim@xxxxxxxxx>
> ---
> include/linux/writeback.h | 2 +-
> mm/page-writeback.c | 31 ++++++++++++++++---------------
> mm/vmscan.c | 2 +-
> 3 files changed, 18 insertions(+), 17 deletions(-)
>
> diff --git a/include/linux/writeback.h b/include/linux/writeback.h
> index 335dba1..1bacdda 100644
> --- a/include/linux/writeback.h
> +++ b/include/linux/writeback.h
> @@ -97,7 +97,7 @@ void laptop_mode_timer_fn(unsigned long data);
> #else
> static inline void laptop_sync_completion(void) { }
> #endif
> -void throttle_vm_writeout(gfp_t gfp_mask);
> +void throttle_vm_writeout(gfp_t gfp_mask, struct mem_cgroup *mem_cgroup);
>
> /* These are exported to sysctl. */
> extern int dirty_background_ratio;
> diff --git a/mm/page-writeback.c b/mm/page-writeback.c
> index d717fa9..bf85062 100644
> --- a/mm/page-writeback.c
> +++ b/mm/page-writeback.c
> @@ -131,18 +131,6 @@ EXPORT_SYMBOL(laptop_mode);
> static struct prop_descriptor vm_completions;
> static struct prop_descriptor vm_dirties;
>
> -static unsigned long dirty_writeback_pages(void)
> -{
> - unsigned long ret;
> -
> - ret = mem_cgroup_page_stat(NULL, MEMCG_NR_DIRTY_WRITEBACK_PAGES);
> - if ((long)ret < 0)
> - ret = global_page_state(NR_UNSTABLE_NFS) +
> - global_page_state(NR_WRITEBACK);
> -
> - return ret;
> -}
> -
Nice cleanup.
> /*
> * couple the period to the dirty_ratio:
> *
> @@ -703,12 +691,25 @@ void balance_dirty_pages_ratelimited_nr(struct address_space *mapping,
> }
> EXPORT_SYMBOL(balance_dirty_pages_ratelimited_nr);
>
> -void throttle_vm_writeout(gfp_t gfp_mask)
> +/*
> + * Throttle the current task if it is near dirty memory usage limits.
> + * If @mem_cgroup is NULL or the root_cgroup, then use global dirty memory
> + * information; otherwise use the per-memcg dirty limits.
> + */
> +void throttle_vm_writeout(gfp_t gfp_mask, struct mem_cgroup *mem_cgroup)
> {
> struct dirty_info dirty_info;
> + unsigned long nr_writeback;
>
> for ( ; ; ) {
> - global_dirty_info(&dirty_info);
> + if (!mem_cgroup || !memcg_dirty_info(mem_cgroup, &dirty_info)) {
> + global_dirty_info(&dirty_info);
> + nr_writeback = global_page_state(NR_UNSTABLE_NFS) +
> + global_page_state(NR_WRITEBACK);
> + } else {
> + nr_writeback = mem_cgroup_page_stat(
> + mem_cgroup, MEMCG_NR_DIRTY_WRITEBACK_PAGES);
In point of view rcu_read_lock removal, memcg can't destroy due to
mem_cgroup_select_victim's css_tryget?
Then, we can remove unnecessary rcu_read_lock in mem_cgroup_page_stat.
--
Kind regards,
Minchan Kim
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