dentry cache grows to really large number on 64bit machine

dentry cache grows to really large number on 64bit machine

[Kunal Trivedi]

Hi,
I am running 2.6.18 kernel on 64 bit AMD machine. (procinfo attached
at the end of the mail). One of the things I have noticed that
dentry_cache grows really fast under certain code path.
So, far I have not seen any problems, but I would like to get some
more input on this subject. Is it okay for dentry_cache to grow that
much ?

I've run following program for an ~1.00 hour. And my slabinfo shows following.

# cat /proc/slabinfo | grep dentry
dentry_cache      5228333 5228333    224   17    1 : tunables  120
60    8 : slabdata 307549 307549      0


# cat /proc/meminfo
MemTotal:      8173080 kB
MemFree:       6787852 kB
Buffers:         42048 kB
Cached:          72616 kB
SwapCached:          0 kB
Active:          88608 kB
Inactive:        29796 kB
HighTotal:           0 kB
HighFree:            0 kB
LowTotal:      8173080 kB
LowFree:       6787852 kB
SwapTotal:     2096472 kB
SwapFree:      2096472 kB
Dirty:              48 kB
Writeback:           0 kB
AnonPages:        3716 kB
Mapped:           3336 kB
Slab:          1251292 kB
PageTables:        192 kB
NFS_Unstable:        0 kB
Bounce:              0 kB
CommitLimit:  10269552 kB
Committed_AS:    11500 kB
VmallocTotal: 34359738367 kB
VmallocUsed:      1272 kB
VmallocChunk: 34359737015 kB
HugePages_Total:     0
HugePages_Free:      0
HugePages_Rsvd:      0
Hugepagesize:     2048 kB


int
main()
{
    int fd;
    char fname[] = "/tmp/proc-output-XXXXXX";

    fd = mkstemp(fname);
    close(fd);
    unlink(fname);
    return 0;
}

Please advice,

Thanks
-Kunal

Re: dentry cache grows to really large number on 64bit machine

[Kunal Trivedi]

Hi,
Another piece of information...
If i do on shell.

# while 1
# ./grow_dentry
# end
(grow_dentry is C code I've posted in previous msg.)

Then dentry_cache grows really fast.

But if within 'C' code if I write while(1), then everything is okay.
(No substantial growth ).

Thanks
-Kunal

On 12/6/06, Kunal Trivedi <ktrivedilkml@gmail.com> wrote:
> Hi,
> I am running 2.6.18 kernel on 64 bit AMD machine. (procinfo attached
> at the end of the mail). One of the things I have noticed that
> dentry_cache grows really fast under certain code path.
> So, far I have not seen any problems, but I would like to get some
> more input on this subject. Is it okay for dentry_cache to grow that
> much ?
>
> I've run following program for an ~1.00 hour. And my slabinfo shows following.
>
> # cat /proc/slabinfo | grep dentry
> dentry_cache      5228333 5228333    224   17    1 : tunables  120
> 60    8 : slabdata 307549 307549      0
>
>
> # cat /proc/meminfo
> MemTotal:      8173080 kB
> MemFree:       6787852 kB
> Buffers:         42048 kB
> Cached:          72616 kB
> SwapCached:          0 kB
> Active:          88608 kB
> Inactive:        29796 kB
> HighTotal:           0 kB
> HighFree:            0 kB
> LowTotal:      8173080 kB
> LowFree:       6787852 kB
> SwapTotal:     2096472 kB
> SwapFree:      2096472 kB
> Dirty:              48 kB
> Writeback:           0 kB
> AnonPages:        3716 kB
> Mapped:           3336 kB
> Slab:          1251292 kB
> PageTables:        192 kB
> NFS_Unstable:        0 kB
> Bounce:              0 kB
> CommitLimit:  10269552 kB
> Committed_AS:    11500 kB
> VmallocTotal: 34359738367 kB
> VmallocUsed:      1272 kB
> VmallocChunk: 34359737015 kB
> HugePages_Total:     0
> HugePages_Free:      0
> HugePages_Rsvd:      0
> Hugepagesize:     2048 kB
>
>
> int
> main()
> {
>     int fd;
>     char fname[] = "/tmp/proc-output-XXXXXX";
>
>     fd = mkstemp(fname);
>     close(fd);
>     unlink(fname);
>     return 0;
> }
>
> Please advice,
>
> Thanks
> -Kunal
>