Quoting r. Mark Seger <[EMAIL PROTECTED]>: > Subject: Re: Re: performance counters in /sys > > Since I was the one who originally created this topic I'd like to > restate what I said that got this all started. I'm trying to do > relatively lightweight monitoring of lots of system performance counters > (on the order of 100-200 or more) across a number of subsystems using > standard interfaces. While I don't feel the need to be able to take > 10Ks of samples/sec I would like to at least run efficiently at 1-10/sec > range. I also want to avoid writing custom kernel code and/or talking > directly to hardware. > > As I said in my base note I'm currently reading from /proc while some > sets of counters are better organized than others, I can still access > them relatively efficiently. While I could certainly "get by" reading > one variable per file, I do worry about the overhead as the sampling > frequency goes down. This will also be a problem as the number of > counters and devices grow. The suggestion about using perfquery would > certainly work, but I'd also be concerned about the overhead in running > it at smaller sampling intervals. > > I certainly understand the desire to move to sysfs and that > /usr/src/linux/Documentation/filesystems/sysfs.txt states that "Mixing > types, expressing multiple lines of data, and doing fancy formatting of > data is heavily frowned upon. Doing these things may get you publically > humiliated and your code rewritten without notice." However, I don't > read this to mean you must only have one data item per file. For > example, I took a look at /sys/block/hda/stat because one of the types > of data I collect is disk stats and I was wondering how sysfs dealt with > them. Sure enough, they're all in one file per disk as shown below: > > dl380-2: cat /sys/block/hda/stat > 0 0 0 0 0 0 0 > 0 0 0 0 > > Also note some of these count bytes, some sectors and other jiffies, so > even the units need not be identical. > > -mark
So, what about an actual benchmark for the two approaches that were proposed (perfquery / sysfs)? -- MST - Michael S. Tsirkin _______________________________________________ openib-general mailing list [email protected] http://openib.org/mailman/listinfo/openib-general To unsubscribe, please visit http://openib.org/mailman/listinfo/openib-general
