Re: [RFC] parallel directory operations

bzzz@tmi.comex.ru
Tue, 08 Jul 2003 15:50:27 +0000


>>>>> Andi Kleen (AK) writes:

AK> On Tue, 08 Jul 2003 15:28:27 +0000
AK> bzzz@tmi.comex.ru wrote:

>> dynlocks implements 'lock namespace', so you can lock A for namepace N1 and
>> lock B for namespace N1 and so on. we need this because we want to take lock
>> on _part_ of directory.

AK> Ok, a mini database lock manager. Wouldn't it be better to use a small hash
AK> table and lock escalation on overflow for this? Otherwise you could
AK> have quite a lot of entries queued up in the list if the server is slow.

well, it makes sense. AFAIU, only problem with this solution is that we need
very well-tuned hash function. BTW, dynlocks are taken for operation time only.
so, in most often case, for dir entry creation/lookup we need two locks: one for
dcache locking and another for htree's leaf locking.

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