>>>>> Michael Tokarev (MT) writes: MT> Hmm. So where's the elevator level - before raid level (between e.g. MT> a filesystem and md), or after it (between md and physical devices) ? in the both, because raid5 produces _new_ requests and send them to elevator again. MT> I mean, mergeing bios into larger requests makes alot of sense between MT> a filesystem and md levels, but it makes alot less sense to do that MT> between md and physical (fsvo "physical" anyway) disks. i'm not talking about merging small _incoming_ requests. the problem is that a filesystem sends big requests to raid5 (say, 1MB) and then raid5 produces ton of small requests (PAGE_SIZE) to handle that 1MB one. this kills performance. thanks, Alex - 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
