On Thu, 2006-02-16 at 23:08 +0100, Jesper Juhl wrote: > On 2/16/06, Andi Kleen <[email protected]> wrote: > > On Thursday 16 February 2006 22:46, Jesper Juhl wrote: > > > > > Obviously something is wrong, but I just can't seem to spot it. Any clues? > > > > It's a bitmap. 3 = 0b11 > > > > When I was reading the smpboot code my brain *was* actually in the > "this is a bitmap" mode, but when I then looked at the sysfs code it > for some reason switched to "this wants to just print the number of > siblings as an integer" mode - which was obviously where I went wrong. > If it's being treated as a bitmap when it's created why would that > change when it gets printed - D'OH! > > Thank you very much for that hit with the clue stick Andi. While looking around for other examples, I ran across cpufreq/affected_cpus. Shouldn't cpufreq.c:show_affected_cpus() be using cpumask_scnprintf instead of "%u"? But anyway... It seems to me that this could be confusing for a lot of people who are casually browsing through sysfs. Why not name core_siblings something like core_sibling_bitmap? Using _units isn't unprecedented, we have read_ahead_kb. I think it's nice not having to look it up to know read_ahead is in kb and not bytes or sectors. Likewise, it'd be nice to know it's a bitmap and not a count just by looking at the name. More alternatively, bitmaps seem ugly. Why not one of these options instead? - a space separated list of bitmap offsets: "0 1" instead of 3 - a directory of symlinks to devices/system/cpu/cpu[N]: devices/system/cpu/cpu1/topology/core_siblings/0 -> ../../../cpu0 devices/system/cpu/cpu1/topology/core_siblings/1 -> ../../../cpu1 -- Zan Lynx <[email protected]>
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