On Sat, Aug 21, 2010 at 07:51:38AM +0800, Michael Rubin wrote: > On Fri, Aug 20, 2010 at 3:08 AM, Wu Fengguang <fengguang.wu@xxxxxxxxx> wrote: > > How about the names nr_dirty_accumulated and nr_writeback_accumulated? > > It seems more consistent, for both the interface and code (see below). > > I'm not really sure though. > > Those names don't seem to right to me. > I admit I like "nr_dirtied" and "nr_cleaned" that seems most > understood. These numbers also get very big pretty fast so I don't > think it's hard to infer. That's fine. I like "nr_cleaned". > >> In order to track the "cleaned" and "dirtied" counts we added two > >> vm_stat_items. Per memory node stats have been added also. So we can > >> see per node granularity: > >> > >> # cat /sys/devices/system/node/node20/writebackstat > >> Node 20 pages_writeback: 0 times > >> Node 20 pages_dirtied: 0 times > > > > I'd prefer the name "vmstat" over "writebackstat", and propose to > > migrate items from /proc/zoneinfo over time. zoneinfo is a terrible > > interface for scripting. > > I like vmstat also. I can do that. Thank you. > > Also, are there meaningful usage of per-node writeback stats? > > For us yes. We use fake numa nodes to implement cgroup memory isolation. > This allows us to see what the writeback behaviour is like per cgroup. That's sure convenient for you, for now. But it's special use case. I wonder if you'll still stick to the fake NUMA scenario two years later -- when memcg grows powerful enough. What do we do then? "Hey let's rip these counters, their major consumer has dumped them.." For per-job nr_dirtied, I suspect the per-process write_bytes and cancelled_write_bytes in /proc/self/io will serve you well. For per-job nr_cleaned, I suspect the per-zone nr_writeback will be sufficient for debug purposes (in despite of being a bit different). > > The numbers are naturally per-bdi ones instead. But if we plan to > > expose them for each bdi, this patch will need to be implemented > > vastly differently. > > Currently I have no plans to do that. Peter? :) Thanks, Fengguang -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
