/ 2006-12-23 07:40:18 +1100 \ Neil Brown: > On Friday December 22, Lars.Ellenberg@xxxxxxxxxx wrote: > > > > md raidX make_request functions strip off the BIO_RW_SYNC flag, > > this introducing additional latency. > > > > below is a suggested patch for the raid1.c . > > other suggested solutions would be to let the bio_clone do its work, > > and not reassign thereby stripping off all flags. > > at most strip off known unwanted flags (the BARRIER flag). > > > > similar pattern in the other raid versions. > > Thanks. I think your patch is appropriate. > I don't like the idea of passing down any flags by default. If a flag > makes failure more likely (like BIO_RW_AHEAD or BIO_RW_FAILFAST) then > I *don't* want it passed down without making a conscious decision that > it is a good idea. > > So yes, _SYNC should be passed down in raid1/raid10. More interesting > stuff would be needed in raid456. > _FAILFAST should probably never be passed down (well, maybe in > multipath, but who uses md/multipath??) > _META ... what is that ?? I'm not passing it down until I know!! > > I'll look into this after the holidays. Meanwhile if you want to be > certain that this is in 2.6.20, > - Fix the retry-read case as well (where ->bi_rw is assigned about > 10 lines from the end of raid1d() I don't think thats necessary, since an explicit unplug is in place there. but ok. > - Create a 'perfect patch', > - add Acked-by: NeilBrown <neilb@xxxxxxx> > - and post it to akpm@xxxxxxxx (and appropriate lists). -- : Lars Ellenberg Tel +43-1-8178292-55 : : LINBIT Information Technologies GmbH Fax +43-1-8178292-82 : : Vivenotgasse 48, A-1120 Vienna/Europe http://www.linbit.com : - To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
