Oleg, Peter, Ingo, Andi & Preeti, 2013/1/2 Jiri Slaby <jslaby@xxxxxxx>: > On 01/02/2013 04:21 PM, Ivo Sieben wrote: >> I don't understand your responses: do you suggest to implement this >> "if active" behavior in: >> * A new wake_up function called wake_up_if_active() that is part of >> the waitqueue layer? > > Sounds good. > > -- > js > suse labs I want to ask you 'scheduler' people for your opinion: Maybe you remember my previous patch where I suggested an extra 'waitqueue empty' check before entering the critical section of the wakeup() function (If you do not remember see https://lkml.org/lkml/2012/10/25/159) Finally Oleg responded that a lot of callers do if (waitqueue_active(q)) wake_up(...); what made my patch pointless and adds a memory barrier. I then decided to also implement the 'waitqueue_active' approach for my problem. But now I get a review comment by Jiri that he would like to hide this 'if active behavior' in a wake_up_if_active() kind of function. I think he is right that implementing this check in the wakeup function would clean things up, right? I would like to have your opinion on the following two suggestions: - We still can do the original patch on the wake_up() that I suggested. I then can do an additional code cleanup patch that removes the double 'waitqueue_active' call (a quick grep found about 150 of these waitqueue active calls) on several places in the code. - Or - as an alternative - I could add extra _if_active() versions of all wake_up() functions, that implement this extra test. Regards, Ivo -- To unsubscribe from this list: send the line "unsubscribe linux-serial" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
