Re: [PATCH RFC 1/8] dcache: show count of hash buckets in sysctl fs.dentry-state

Konstantin Khlebnikov
2020-05-08T16:16:48Z

On 08/05/2020 17.49, Waiman Long wrote:
> On 5/8/20 8:23 AM, Konstantin Khlebnikov wrote:
>> Count of buckets is required for estimating average length of hash chains.
>> Size of hash table depends on memory size and printed once at boot.
>>
>> Let's expose nr_buckets as sixth number in sysctl fs.dentry-state
>
> The hash bucket count is a constant determined at boot time. Is there a need to use up one dentry_stat entry for that? Besides one can get
> it by looking up the kernel dmesg log like:
>
> [    0.055212] Dentry cache hash table entries: 8388608 (order: 14, 67108864 bytes)

Grepping logs since boot time is a worst API ever.

dentry-state shows count of dentries in various states.
It's very convenient to show count of buckets next to it,
because this number defines overall scale.

>
> Cheers,
> Longman
>