Re: [PATCH] improved locking performance in rt_run_flush()

[Herbert Xu]

David Miller <davem@xxxxxxxxxxxxx> wrote:
> From: Dave Johnson <djohnson+linux-kernel@xxxxxxxxxxxxxxxxxxxxxx>
>> 
>> The below patch changes rt_run_flush() to only take each spinlock
>> protecting the rt_hash_table once instead of taking a spinlock for
>> every hash table bucket (and ending up taking the same small set 
>> of locks over and over).

...

> I'm not ignoring it I'm just trying to brainstorm whether there
> is a better way to resolve this inefficiency. :-)

The main problem I see with this is having to walk and free each
chain with the lock held.  We could avoid this if we had a pointer
in struct rtable to chain them up for freeing later.

I just checked and struct rtable is 236 bytes long on 32-bit but
the slab cache pads it to 256 bytes so we've got some free space.
I suspect 64-bit should be similar.

Cheers,
-- 
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Email: Herbert Xu ~{PmV>HI~} <herbert@xxxxxxxxxxxxxxxxxxx>
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