Thomas Gleixner wrote: > > We'd like to announce a brand new implementation of performance counter > support for Linux. It is a very simple and extensible design that has the > potential to implement the full range of features we would expect from such > a subsystem. > First of all, let me say I really like what I've seen so far. The file descriptor paradigm seems really elegant to me. > - Only one single new system call is needed: sys_perf_counter_open(). > All performance-counter operations are implemented via standard > VFS APIs such as read() / fcntl() and poll(). As previously discussed, I think this should be a filesystem rather than a system call. There are a couple of advantages to doing it that way, IMO: - Strings, rather than numbers, which means fewer constraints across architectures. - The events available can be exported in the filesystem itself (via readdir) rather than via sysfs. - Compatibility with existing tools, esp. non-C tools. I'm thinking of something like: /dev/perfctr/3/cache_misses/all/simple/300 i.e. /dev/perfctr/<cpu>/<event>/<pid>/<type>/<period>. I am putting <cpu> ahead of <event> in the hierarchy, so a readdir() on the <cpu> directory can show the events available by name on that CPU. Raw hardware events can be accessed by something like /dev/perfctr/<cpu>/0x4064/... -hpa -- To unsubscribe from this list: send the line "unsubscribe linux-arch" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
