Re: Limit hash table size

[Andrew Morton <akpm@osdl.org>]

Andi Kleen <ak@suse.de> wrote:
>
> On Wed, 04 Feb 2004 22:06:42 -0600
> Steve Lord <lord@xfs.org> wrote:
> 
> 
> > It does look like 2.6 does better, but I don't have quite the
> > amount of memory on my laptop....
> 
> I see the problem on a 8GB x86-64 box with 2.6.2-rc1. 

I see no problem here.  I see a kernel which is designed to address a mix
of workloads only being tested for one particular workload.

> After a find / I have:
> 
>  Active / Total Objects (% used)    : 1794827 / 1804510 (99.5%)
>  Active / Total Slabs (% used)      : 125647 / 125647 (100.0%)
>  Active / Total Caches (% used)     : 71 / 112 (63.4%)
>  Active / Total Size (% used)       : 685008.27K / 686856.36K (99.7%)
>  Minimum / Average / Maximum Object : 0.02K / 0.38K / 128.00K
> 
>   OBJS ACTIVE  USE OBJ SIZE  SLABS OBJ/SLAB CACHE SIZE NAME                   
> 708600 708559  99%    0.25K  47240       15    188960K dentry_cache
> 624734 624128  99%    0.69K  56794       11    454352K reiser_inode_cache
> 254200 253514  99%    0.09K   6355       40     25420K buffer_head
> 109327 109253  99%    0.06K   1853       59      7412K size-64
> 
> Now I allocate 6GB of RAM. After that:
> 
>  Active / Total Objects (% used)    : 741266 / 1092573 (67.8%)
>  Active / Total Slabs (% used)      : 78291 / 78291 (100.0%)
>  Active / Total Caches (% used)     : 71 / 112 (63.4%)
>  Active / Total Size (% used)       : 339837.24K / 455189.93K (74.7%)
>  Minimum / Average / Maximum Object : 0.02K / 0.42K / 128.00K
> 
>   OBJS ACTIVE  USE OBJ SIZE  SLABS OBJ/SLAB CACHE SIZE NAME                   
> 464497 381126  82%    0.69K  42227       11    337816K reiser_inode_cache
> 391545 192481  49%    0.25K  26103       15    104412K dentry_cache
> 135840  95304  70%    0.09K   3396       40     13584K buffer_head

The caches were shrunk by around 40%.  Looks good.

> 1GB of dentry cache seems to be quite excessive.

Not if your workload wants to use those dentries again.  You've only
conducted one particular test.