Messages in this thread |  | | Date | Wed, 18 Sep 2002 07:28:23 -0700 | From | William Lee Irwin III <> | Subject | Re: [patch] lockless, scalable get_pid(), for_each_process() elimination, 2.5.35-BK |
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On Wed, Sep 18, 2002 at 12:11:30PM +0200, Ingo Molnar wrote: > so i think the most we could get is to actually eliminate the pidhash and > use the idtag hash for it. This would concentrate all the performance > efforts on the idtag hash.
I eventually had special-case handling of IDTAG_PID so that it did not use idtags, but chained tasks directly, and removing the pidhash as goals.
On Wed, Sep 18, 2002 at 12:11:30PM +0200, Ingo Molnar wrote: > another, locking improvement is possible as well: > - the idtag spinlock should be eliminated, we can reuse the tasklist lock > for it - in the exit and fork path we hold it already. This also means > we can walk an ID list by read-locking the tasklist lock. > the idtag spinlock is already superfluous i think, because the idtag task > list is only safely walked if we read-lock the task list. So it's not like > anyone could hash in a new idtag while we walk the list. > What do you think?
ISTR the idtag_lock was for cases where the hashtable was modified while the tasklist_lock was only held for reading. Basically, once those are resolved, the idtag_lock goes away.
Cheers, Bill - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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