[9fans] leak/umem question

[erik quanstrom <quanstro@coraid.com>]

i have a process (modified upas/fs) that has quite a large amount
of allocation churn.  on startup, its memory footprint looks like this:
	quanstro       6305    0:00   0:00     6264K Pread    8.out
umem reports this
 73023     4673712 henter+0x8e
  2435      702224 newmessage+0x16
  2434      405776 badd+0x24
   900       60000 strdup+0x20
   868       94176 parseunix+0x27
     4         384 newfid+0x5a
     3       91200 erealloc+0x25
     1         480 newmbox+0x15
     1         224 dirfstat+0x29
     1          32 mdirmbox+0x7d
after churning through the whole mail box, the image now looks like
this
	quanstro       6305    0:17   0:10    32468K Pread    8.out
leak says no blocks are leaked and umem gives an identical report to
the first:
 73023     4673712 henter+0x8e
  2435      702224 newmessage+0x16
  2434      405776 badd+0x24
   900       60000 strdup+0x20
   868       94176 parseunix+0x27
     4         384 newfid+0x5a
     3       91200 erealloc+0x25
     1         480 newmbox+0x15
     1         224 dirfstat+0x29
     1          32 mdirmbox+0x7d
if i use leak -b, the image generated is all light/dark blue with just a
few white pixels at the beginning and end.  there is no apparent free space.
the image is at www.quanstro.net / leak.png.

where is the "missing" 28mb going to?

- erik