On Tue, Apr 21, 2015 at 10:12 AM, Jens Axboe <axboe@xxxxxx> wrote: > On 04/21/2015 11:09 AM, Ming Lin wrote: >> >> Hi Jens, >> >> This RFC DRAFT patch is on top of your "[PATCH v2] Support for write >> stream IDs" >> I throw it out early to get comments if it's the way to go. >> >> Quote LWN(http://lwn.net/Articles/638722): >> >> "There would be clear value in a closer association between stream IDs >> and specific buffered-write operations. Getting there would require >> storing >> the stream ID with each dirtied page, though; that, in turn, almost >> certainly >> implies shoehorning the stream ID into the associated page structure. >> That would not be an easy task; it is not surprising that it is not a part >> of >> this patch set. Should the lack of per-buffered-write stream IDs prove to >> be >> a serious constraint in the future, somebody will certainly be motivated >> to >> try to find a place to store another eight bits in struct page." >> >> This draft patch stores stream_id in buffer head instead of page. > > > This is pointless. You need to store it in the page, if the whole point is > that you want this to be trackable. And adding it to struct page would be a > no-go, we can't increase the size of that. See various other discussions > around, for instance, IO priorities for buffered writeback and tracking that > state on the side. I googled, but didn't find related discussions. Could you please point me a link? Thanks. -- 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
