[lkml]   [1998]   [Nov]   [16]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
SubjectRe: elevator algorithm bug in ll_rw_blk.c
> With that kind of knowledge, what kind of improvements could be made to
> the driver?

actually, it's the true geometry that a disk scheduler wants,
along with a model for how long a given seek will take.
hdparm gives neither: the geometry is false, because all non-ancient
disks are zoned, and it doesn't mention seeking (which is a
nonlinear function in any case), or head-switching time.

fortunately, none of this matters much, since seeking is still basically
monotonic with distance in _blocks_. this is why the current request
sorting (even before the fix) can easily deliver maximal bandwidth.
it basically only errs when you generate a new request at a lower
absolute address (thus deferred by the sort), that in truth is in
the current track, and would be very fast to fetch. that's a fairly
obscure pattern...

regards, mark hahn.

To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to
Please read the FAQ at

 \ /
  Last update: 2005-03-22 13:45    [W:0.029 / U:0.372 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site