Hello, Andrew. On Fri, Dec 21, 2012 at 06:15:23PM -0800, Andrew Morton wrote: > On Fri, 21 Dec 2012 17:57:15 -0800 Tejun Heo <t...@kernel.org> wrote: > > > There's no need to test whether a (delayed) work item in pending > > before queueing, flushing or cancelling it. Most uses are unnecessary > > and quite a few of them are buggy. > > > - if (!work_pending(&ipc_memory_wq)) > > - schedule_work(&ipc_memory_wq); > > + schedule_work(&ipc_memory_wq); > > Well, the new code is a ton slower than the old code if the work is > frequently pending, so some care is needed with such a conversion.
Yeah, I mentioned it in the head message. it comes down to test_and_set_bit() vs. test_bit() and none of the current users seems to be hot enough for that to matter at all. In very hot paths, such optimization *could* be valid. The problem is that [delayed_]work_pending() seem to be abused much more than they are put to any actual usefulness. Maybe we should rename them to something really ugly. I don't know. > That's not an issue for the IPC callsite - memory offlining isn't > frequent. > > > ... > > > > Please let me know how this patch should be routed. I can take it > > through the workqueue tree if necessary. > > > > Please merge this one yourself. Can I add your acked-by? Thanks. -- tejun -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
