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Re: 7feee74: MDEV-7943 - pthread_getspecific() takes 0.76% in OLTP RO
On Fri, May 08, 2015 at 07:01:11PM +0200, Sergei Golubchik wrote:
> Hi, Sergey!
> On Apr 22, svoj@xxxxxxxxxxx wrote:
> > revision-id: 7feee74dd30c96bd50d1c90e4ce3b06a656b17a5
> > parent(s): 696188fe2f0756a98914df5b95ba302f7e5c55df
> > committer: Sergey Vojtovich
> > branch nick: mariadb
> > timestamp: 2015-04-22 13:29:56 +0400
> > message:
> > MDEV-7943 - pthread_getspecific() takes 0.76% in OLTP RO
> > Added THD argument to select_result and all derivative classes. This
> > reduces number of pthread_getspecific calls from 796 to 776 per OLTP
> > RO transaction.
> Lots of changes for a little gain :)
Gain is a bit undervalued here. This patch covers a lot more than OLTP RO.
OLTP RO part is like 10% of it. :)
> Ok to push.
> An idea. Create a variant of Sql_alloc (say, Sql_alloc_explicit, a
> parent of Sql_alloc) that does not use current_thd but requires MEM_ROOT
> to be specified explicitly. And use it for classes where you want it.
That's a very good idea. We should try to prevent further usage of Sql_alloc
with implicit mem_root. But since I want explicit Sql_alloc basically everywhere
I'd rather do it another way around: add Sql_alloc_implicit instead and use
Sql_alloc in fixed code. :)