Martin Steigerwald wrote: > At the moment it appears to me that disabling write cache may often give > more performance than using barriers. And this doesn't match my > expectation of write barriers as a feature that enhances performance. Why do you have that expectation? I've never seen barriers advertised as enhancing performance. :) I do wonder why barriers on, write cache off is so slow; I'd have thought the barriers were a no-op. Maybe I'm missing something. > Right now a "nowcache" option and having this as default appears to make > more sense than defaulting to barriers. I don't think that turning off write cache is something the filesystem can do; you have to take that as an administrative step on your block devices. > But I think this needs more > testing than just those simple high meta data load tests. Anyway I am > happy cause I have a way to speed up XFS ;-). My only hand-wavy concern is whether this has any adverse physical effect on the drive (no cache == lots more head movement etc?) but then barriers are constantly flushing/invalidating that cache, so it's probably a wash. And really, I have no idea. :) -Eric -- 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
