On 01/07, Martin Schwidefsky wrote: > > On Wed, 6 Jan 2010 12:56:33 -0800 (PST) > Roland McGrath <roland@xxxxxxxxxx> wrote: > > > In other circumstances with utrace, it is very possible to wind up with > > user_disable_single_step being called superfluously when there was no > > stop (and so not necessarily any context switch or other high overhead). > > On other machines, user_disable_single_step is pretty cheap even where > > user_enable_single_step is quite costly. Given how simple and cheap it > > is to short-circuit the excess work on s390, I think it is worthwhile. > > We could use the same compare of the control registers as the code in > __switch_to. See below. FYI, I tested your c3311c13adc1021e986fef12609ceb395ffc5014 commit which does this optimization (compared to the patch you sent previously), it works fine. But please see another email I am going to send... Oleg. -- To unsubscribe from this list: send the line "unsubscribe linux-s390" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
