Guys,
I met a puzzle when I work with my amd64 box. When I observe a stream
slab of 2048 sizes, the "buf in use", "buf total" and "memory in use"
seems to mean different thing between 32/64 bit kernels.
I allocated mbuf of 1600 bytes,
In 64-bit mode, the cache name of 2048 should have name of
"streams_dblk_1936", output like below:
cache buf buf buf memory alloc alloc
name size in use total in use succeed fail
------------------------- ------ ------ ------ --------- --------- -----
streams_dblk_1936 2048 602 602 2465792 1382 0
While with 32-bit mode, with the name of "streams_dblk_1984", output
like below:
cache buf buf buf memory alloc alloc
name size in use total in use succeed fail
------------------------- ------ ------ ------ --------- --------- -----
streams_dblk_1984 2048 600 603 1372160 608 0
My first question is: why in 64-bit kernel, the "memory in use" = ("buf
in use" + "buf total") * "buf size"?
And we see in 32-bit kernel, it is "buf total" * "buf size".
Another thing I don't understand is my driver allocated 600 mblk of 1600
Bytes during attach. After rem_drv, I found in 64-bit kernel, kmastat
reports below:
cache buf buf buf memory alloc alloc
name size in use total in use succeed fail
------------------------- ------ ------ ------ --------- --------- -----
streams_dblk_1936 2048 2 2 8192 1493 0
"buf total" also reduced by 600 after freemsg. And it seems next time
allocate, stream module will allocate new area of streams_dblk_1936.
While on 32-bit kernel, the streams_dblk_1984 seems to be still there:
cache buf buf buf memory alloc alloc
name size in use total in use succeed fail
------------------------- ------ ------ ------ --------- --------- -----
streams_dblk_1984 2048 0 603 1372160 608 0
Why "buf total" still 603?
Thanks,
Raymond
