On Tue, Sep 23 2008, Martin Steigerwald wrote: > Am Dienstag, 23. September 2008 schrieb Aaron Carroll: > > Martin Steigerwald wrote: > > > Hi! > > > > > > I am searching documentation about CFQ io scheduler. I can't find it in > > > linux 2.6.26 Documentation directory. > > > > > > I found about these in german[1]: > > > > > > back_seek_max:16384 > > > back_seek_penalty:2 > > > fifo_expire_async:250 > > > fifo_expire_sync:123 > > > quantum:4 > > > > > > But I am completely missing about these: > > > > > > slice_async:40 > > > > Base length of an asynchronous queue timeslice (that is, how long the > > queue has to dispatch requests each round). The actual timeslice > > length is scaled by the I/O priority. > > [...] > > Thanks. As I do not find documentation about CFQ at all, I think I need to > create a new file from scratch... how about > Documentation/block/cfq-iosched.txt? That would be great! > For that I need some more information about CFQ. I found the following > resources: > > - CFQ V3 aka CFQ TS: http://lwn.net/Articles/143474/, > http://lwn.net/Articles/114770/ and posts by Jens, > http://lwn.net/Articles/113869/ > > - CFQ V2: Post by Jens, http://lwn.net/Articles/101029/ > > - CFQ: Post by Jens, http://lwn.net/Articles/22429/ You can mention the links for v1 and v2, but as they have even little historic relevance, don't spend more time on that. > - Documentation/block/as-iosched.txt / deadline-iosched.txt (as for how an IO > scheduler can be documented) > > Would that be what I should read in order to write such an documentation? Yes > How about the relevance of CFQ and CFQ v2 stuff? What of it would be good to > mention? I would like to limit documentation to what is still relevant for > the current implementation of the IO scheduler. Should I mention its > inheritance from SFQ - maybe in a small introduction and historic overview? Even the very first CFQ posted used per-process queues, so there's really very little inheritance from SFQ at all. So I don't think it's particularly interesting to mention. But if you want, go ahead :-) -- Jens Axboe -- 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
