On 10/29/2018 05:23 PM, Vito Caputo wrote: > On Mon, Oct 29, 2018 at 04:59:03PM -0400, Waiman Long wrote: >> On 10/29/2018 04:38 PM, Davidlohr Bueso wrote: >>> On Mon, 29 Oct 2018, Waiman Long wrote: >>> >>>> BTW, since you are making stat2 compatible with stat, will that be >>>> easier from the user API perspective if we use a sysctl parameter to >>>> turn on and off IRQs reporting for /proc/stat, for example? >>> For one /proc/stat is also common for debugging envs (ie: performance) >>> and I fear that if a tunnable modifies the behavior of the output, we >>> it might never be usable again (at least not without having users also >>> now consider the systctl parameter). Making it dynamic I think is not >>> worth it. >>> >>> Thanks, >>> Davidlohr >> This is just a matter if it is easier for users to modify their code to >> use /proc/stat2 or turning on a sysctl parameter. Again, this will >> certainly depend on the circumstances. >> > I wonder if it makes sense to introduce a more general mechanism for > toggling subfields in proc files. Extended attributes could probably be > abused to key the subfields, write a 1 or 0 to well-known names for > toggling them on a per-fd basis via fsetxattr. > > For this particular case the program would just have to add code like: > > int zero = 0; > fsetxattr(proc_stat_fd, "intr", &zero, sizeof(zero), XATTR_REPLACE); > > Just putting it out there. I've certainly wanted an ability to noop > fields before where I was polling proc frequently and skipping the bulk > of what was there but syscpu was still rather high. > > I'm definitely not in favor of just adding another stat file that is the > same format as the existing one with the intrs zeroed out. It's a dirty > hack; fine for your local needs but too gross for upstream IMHO. > > Regards, > Vito Caputo Does procfs allow extended attributes? I am not sure if using extended attributes is a usual practice for doing this kind of control on a procfs file. Cheers, Longman
