Hello, Josef.
On Tue, Oct 25, 2016 at 02:41:41PM -0400, Josef Bacik wrote:
> These are counters that constantly go up in order to do bandwidth
> calculations.
> It isn't important what the units are in, as long as they are consistent
> between
> the two of them, so convert them to count bytes written/dirtied, and allow the
> metadata accounting stuff to change the counters as well.
>
> Signed-off-by: Josef Bacik <jba...@fb.com>
Acked-by: Tejun Heo <t...@kernel.org>
A small nit below.
> @@ -2547,12 +2547,16 @@ void account_page_redirty(struct page *page)
> if (mapping && mapping_cap_account_dirty(mapping)) {
> struct inode *inode = mapping->host;
> struct bdi_writeback *wb;
> + unsigned long flags;
> bool locked;
>
> wb = unlocked_inode_to_wb_begin(inode, &locked);
> current->nr_dirtied--;
> - dec_node_page_state(page, NR_DIRTIED);
> - dec_wb_stat(wb, WB_DIRTIED);
> +
> + local_irq_save(flags);
> + __dec_node_page_state(page, NR_DIRTIED);
> + __add_wb_stat(wb, WB_DIRTIED_BYTES, -(long)PAGE_SIZE);
> + local_irq_restore(flags);
Hmmm... so, the explicit irq clustering is neutral or win as the code
currently stands but AFAICS that's just because add_wb_stat() doesn't
use the right percpu ops. If we convert add_wb_stat() to use the
matching percpu ops, the above change would be more expensive at least
on x86. Maybe just skip this part?
Thanks.
--
tejun
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