On Mon, Nov 26, 2018 at 12:32:18PM -0500, Johannes Weiner wrote: > On Mon, Nov 26, 2018 at 04:54:47PM +0000, Mel Gorman wrote: > > On Mon, Nov 26, 2018 at 11:07:24AM -0500, Johannes Weiner wrote: > > > @@ -509,6 +509,15 @@ config PSI > > > > > > Say N if unsure. > > > > > > +config PSI_DEFAULT_DISABLED > > > + bool "Require boot parameter to enable pressure stall information tracking" > > > + default n > > > + depends on PSI > > > + help > > > + If set, pressure stall information tracking will be disabled > > > + per default but can be enabled through passing psi_enable=1 > > > + on the kernel commandline during boot. > > > + > > > endmenu # "CPU/Task time and stats accounting" > > > > > > > Should this default y on the basis that someone only wants the feature if > > they are aware of it? This is not that important as CONFIG_PSI is disabled > > by default and it's up to distribution maintainers to use their brain. > > I went with the NUMA balancing example again here, which defaults to > enabling the feature at boot time. IMO that makes sense, as somebody > would presumably first read through the PSI help text, then decide y > on that before being asked the second question. A "yes, but > <stipulations>" for vendor kernels seems more appropriate than > requiring a double yes for other users to simply get the feature. > That's fair enough. The original NUMA balancing thinking was that it should be enabled because there is a reasonable expectation that it would improve performance regardless of user awareness. PSI is not necessarily the same as it requires a consumer but I accept that a distro maintainer should read the Kconfig text and figure it out. I'll make sure the updated version gets tested, thanks. -- Mel Gorman SUSE Labs
