please, try the patch attached.
thanks, Alex
Eric Sandeen wrote:
One thing that seems to be happening is that thanks to delalloc, a nice
big request is coming in (only 1036 blocks of the 4096, not quite sure
why), but then it gets into ext4_mb_normalize_request(), which finds the
most blocks it can "preallocate" is 256, and chops down the request to
256 blocks. Shouldn't this preallocation be over & above what was asked
for, vs. reducing the request?
Ok, so, we get allocations in 256-block chunks... Why they don't all
come out contiguous, I don't know yet...
-Eric
Index: linux-2.6.24-rc1/fs/ext4/mballoc.c
===================================================================
--- linux-2.6.24-rc1.orig/fs/ext4/mballoc.c 2007-10-27 10:29:17.000000000 +0400
+++ linux-2.6.24-rc1/fs/ext4/mballoc.c 2007-10-27 22:14:54.000000000 +0400
@@ -3088,8 +3088,10 @@ static void ext4_mb_normalize_request(st
break;
}
}
+ size = wind;
+
if (wind == 0) {
- __u64 tstart;
+ __u64 tstart, tend;
/* file is quite large, we now preallocate with
* the biggest configured window with regart to
* logical offset */
@@ -3097,8 +3099,11 @@ static void ext4_mb_normalize_request(st
tstart = ac->ac_o_ex.fe_logical;
do_div(tstart, wind);
start = tstart * wind;
+ tend = ac->ac_o_ex.fe_logical + ac->ac_o_ex.fe_len - 1;
+ do_div(tend, wind);
+ tend = tend * wind + wind;
+ size = tend - start;
}
- size = wind;
orig_size = size;
orig_start = start;
