On 10/10/2011 10:23 PM, Borislav Petkov wrote: > On Mon, Oct 10, 2011 at 11:32:40AM -0400, Srivatsa S. Bhat wrote: >>> The seems like entirely the wrong way to go about solving this problem. >>> >>> The kernel shouldn't be responsible for making hotplug stress tests >>> exclusive with system sleep. Whoever is running those tests should be >>> smart enough to realize what's wrong if system sleep interferes with a >>> test. > > Yes, agreed. And more: I'm still trying to understand why a test case > like that is relevant and needs to be fixed at all. Let me re-formulate > the question: what real world scenario(s) does the case of hibernating > _while_ off- and onlining cores cover? Or are you simply doing kernel > resiliency testing and thought that offlining cores while hibernating > might make sense? > Actually, my whole intention while coming up with this test case was to test the stability/correct operation of the entire suspend/resume call path. And since I found that cpu hotplug is used in that call path I thought of giving it a whirl and finding out if there were any cases that lead to freezing failures and the like. And I did uncover a couple of cases, one after the other. But I do agree that offlining and onlining CPUs while suspending might not seem all that useful or even wise, but like I said, it was designed to bring out such problematic race conditions. So, in the interest of making the important components involved in suspend/resume call path (namely cpu hotplug) more robust and stable, I think it makes sense to fix any issue we hit (atleast when we practically hit it and it is proved that such a scenario is no longer hypothetical). For that, we can either go with the simple one-line fix that I posted earlier (which has got another motivation now, thanks to Borislav) or with this elaborate solution, whichever seems better/worthwhile. If it is still strongly felt that this "bug" is not worth fixing with such mutual exclusion schemes, it will still get solved anyway by applying that one-line patch. > IOW, I still fail to see a strong reason for this needing fixing. > > Thanks. > -- Regards, Srivatsa S. Bhat <srivatsa.bhat@xxxxxxxxxxxxxxxxxx> Linux Technology Center, IBM India Systems and Technology Lab -- To unsubscribe from this list: send the line "unsubscribe linux-doc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
