On Tue, May 30 2006, Mark Lord wrote:
> Linus wrote:
> >(Yes, tagged queueing makes it less of an issue, of course. I know,
>
> My observations with (S)ATA tagged/native queuing, is that it doesn't make
> nearly the difference under Linux that it does under other OSs.
> Probably because our block layer is so good at ordering requests,
> either from plugging or simply from clever disk scheduling.
Hmm well, I have seen 30% performance increase for a random read work
load with NCQ, I'd say that is pretty nice. And of course there's the
whole write cache issue, with NCQ you _could_ get away with playing more
safe and disabling write back caching.
NCQ helps us with something we can never fix in software - the
rotational latency. Ordering is only a small part of the picture.
Plus I think that more recent drives have a better NCQ implementation,
the first models I tried were pure and utter crap. Lets just say it
didn't instill a lot of confidence in firmware engineers at various
unnamed drive companies.
--
Jens Axboe
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
[Index of Archives]
[Kernel Newbies]
[Netfilter]
[Bugtraq]
[Photo]
[Stuff]
[Gimp]
[Yosemite News]
[MIPS Linux]
[ARM Linux]
[Linux Security]
[Linux RAID]
[Video 4 Linux]
[Linux for the blind]
[Linux Resources]
