[lkml]   [2001]   [Feb]   [20]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
SubjectRe: plugging in 2.4. Does it work?
"A month of sundays ago Jens Axboe wrote:"
> On Wed, Feb 21 2001, Peter T. Breuer wrote:
> > Hurrr ... are you saying that the buffers in the bh's in the request are
> > not contiguous? My reading of the make_request code in 2.2 was that
> > they were! Has that changed? There is now a reference to an elevator
> > algorithm in the code, and I can't make out the effect by looking ...
> > I have been copying the buffer in the request as though it were a single
> > contigous whole. If that is not the case, then yes, bang would happen.
> Nothing has changed in this regard at all between 2.2 and 2.4. The
> buffers are guaranteed to be sequentially sector-wise, but definitely
> not contigious in memory!

I recall that in 2.2 the make_request code tested that the
buffers were contiguous in memory. From 2.2.18:

/* Can we add it to the end of this request? */
if (back) {
if (req->bhtail->b_data + req->bhtail->b_size
!= bh->b_data) {
if (req->nr_segments < max_segments)
else break;

It looks to me like it tested that the b_data char* pointers of the
two requests being considered are exactly distant by the declared
size of one.

Is that no longer the case? If so, that's my answer.

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

 \ /
  Last update: 2005-03-22 13:17    [W:0.062 / U:1.556 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site