On 2010-10-15 11:19, Tejun Heo wrote: > Commit f81f2f7c (ubd: drop unnecessary rq->sector manipulation) > dropped request->sector manipulation in preparation for global request > handling cleanup; unfortunately, it incorrectly assumed that the > updated sector wasn't being used. > > ubd tries to issue as many requests as possible to io_thread. When > issuing fails due to memory pressure or other reasons, the device is > put on the restart list and issuing stops. On IO completion, devices > on the restart list are scanned and IO issuing is restarted. > > ubd issues IOs sg-by-sg and issuing can be stopped in the middle of a > request, so each device on the restart queue needs to remember where > to restart in its current request. ubd needs to keep track of the > issue position itself because, > > * blk_rq_pos(req) is now updated by the block layer to keep track of > _completion_ position. > > * Multiple io_req's for the current request may be in flight, so it's > difficult to tell where blk_rq_pos(req) currently is. > > Add ubd->rq_pos to keep track of the issue position and use it to > correctly restart io_req issue.
Thanks Tejun, good to see this one resolved. -- Jens Axboe ------------------------------------------------------------------------------ Download new Adobe(R) Flash(R) Builder(TM) 4 The new Adobe(R) Flex(R) 4 and Flash(R) Builder(TM) 4 (formerly Flex(R) Builder(TM)) enable the development of rich applications that run across multiple browsers and platforms. Download your free trials today! http://p.sf.net/sfu/adobe-dev2dev _______________________________________________ User-mode-linux-user mailing list User-mode-linux-user@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/user-mode-linux-user
