----- Original Message -----
> Hi,
>
> With a ramdump of a system with 386MB of available memory, "kmem -s"
> shows something like this
>
> CACHE NAME OBJSIZE ALLOCATED TOTAL SLABS
> SSIZE
> dd801c00 kmalloc-2048 2048 670869 670960
> 41935 32k
>
> The memory occupied by objects go beyond the total system memory if we
> use the above numbers to calculate that. I think the output is wrong
> because with SLUB, slabs can be of different sizes depending on the
> order of allocation. And here objects are calculated considering slabs
> are of fixed size.
>
> The attached patch worked for me.
>
> Thanks,
> Vinayak
>
Something's not adding up, literally, when I compare the old values
with those shown by your patch.
For examples, without your patch, check just the caches with a single slab page,
like the nfs_commit_data, fuse_inode and bio-2 caches:
crash> kmem -s
CACHE NAME OBJSIZE ALLOCATED TOTAL SLABS SSIZE
ffff880467c36300 nf_conntrack_ffff880065dd8000 312 0 0 0 8k
ffff88046751f900 nf_conntrack_ffff880465411200 312 0 0 0 8k
ffff8804608db000 nfs_direct_cache 352 0 0 0 8k
ffff8804608daf00 nfs_commit_data 680 23 23 1 16k <=
ffff8804608dae00 nfs_read_data 872 447 576 16 32k
ffff8804608dad00 nfs_inode_cache 1048 1315 1364 44 32k
ffff8804608dac00 fscache_cookie_jar 80 256 276 6 4k
ffff88040b958000 fuse_inode 728 21 21 1 16k <=
ffff88046751f800 btrfs_delayed_data_ref 96 0 0 0 4k
ffff88046751f700 btrfs_delayed_ref_head 160 0 0 0 4k
ffff88046751f600 btrfs_delayed_node 304 0 0 0 8k
ffff88046751f500 btrfs_ordered_extent 424 0 0 0 16k
ffff88046751f400 bio-2 320 25 25 1 8k <=
...
Taking their respective object sizes into account:
nfs_commit_data has an object size of 680, and the 16k slab can hold 23 objects:
23 * 680 = 15640
fuse_inode has an object size of 728, and the 16k slab can hold 21 objects:
21 * 728 = 15288
bio-2 has an object size of 320, and the 8k slab can hold 25 objects:
25 * 320 = 8000
With your patch applied, note that those caches show double the number above, or
46, 42 and 50 respectively:
crash> kmem -s
CACHE NAME OBJSIZE ALLOCATED TOTAL SLABS SSIZE
ffff880467c36300 nf_conntrack_ffff880065dd8000 312 0 0 0 8k
ffff88046751f900 nf_conntrack_ffff880465411200 312 0 0 0 8k
ffff8804608db000 nfs_direct_cache 352 0 0 0 8k
ffff8804608daf00 nfs_commit_data 680 46 46 1 16k
ffff8804608dae00 nfs_read_data 872 684 724 15 32k
ffff8804608dad00 nfs_inode_cache 1048 1534 1534 43 32k
ffff8804608dac00 fscache_cookie_jar 80 532 532 6 4k
ffff88040b958000 fuse_inode 728 42 42 1 16k
ffff88046751f800 btrfs_delayed_data_ref 96 0 0 0 4k
ffff88046751f700 btrfs_delayed_ref_head 160 0 0 0 4k
ffff88046751f600 btrfs_delayed_node 304 0 0 0 8k
ffff88046751f500 btrfs_ordered_extent 424 0 0 0 16k
ffff88046751f400 bio-2 320 50 50 1 8k
...
What am I missing?
Dave
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