Re: [PATCH 4/6] bpf: hash: convert per-hashtable lock into per-bucket bit spinlock

From: Ming Lei
Date: Sat Dec 26 2015 - 03:59:03 EST


On Fri, Dec 18, 2015 at 2:20 PM, Alexei Starovoitov
<alexei.starovoitov@xxxxxxxxx> wrote:
> On Wed, Dec 16, 2015 at 02:58:08PM +0800, Ming Lei wrote:
>> On Wed, Dec 16, 2015 at 1:01 PM, Yang Shi <shy828301@xxxxxxxxx> wrote:
>>
>> >
>> > I recalled Steven confirmed raw_spin_lock has the lockdep benefit too in the
>> > patch review for changing to raw lock.
>> >
>> > Please check this thread out
>> > http://lists.openwall.net/netdev/2015/10/31/7
>>
>> OK, looks I was wrong about the lockdep benifit, :-(
>>
>> But for this lock, I think lockdep isn't such important, because it is the
>> intermost lock, and it can be used just for protecting the bucket list
>> and nothing else need to be covered.
>
> I still think that overhead of normal spinlock per bucket is acceptable.
> Makes the whole thing much easier to read.

OK, let's use per-bucket spinlock first.

--
Ming Lei
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