David Chinner wrote:
> Andi, you are complaining to the wrong person about thread counts. I
> live in the world of excessive parallelism and multithreaded I/O. I
> regularly see 4-8p boxes running hundreds to thousands of I/O
> threads on a single filesystem. These are the workloads XFS is
> designed for and we optimise for. A single extra thread is noise....
The other thing this is doing, though, is having an impact on power
usage, I think. Fedora is trying to identify things which wake the CPU
in an effort to reduce power usage if possible.
See for example:
"One of the biggest power problems is apps that wake up the CPU
unnecessarily. With the tickless kernel for x86 (and soon x86_64),
every time this happens it's a chance for power savings lost.
HOW YOU CAN HELP
We'd like to get as many reports of misbehaving apps as possible.
1) Install the 'powertop' package
2) Run it in a terminal window on a reasonably idle system with your
normal combination of apps. (If you run it when you're actively
compiling a kernel, watching a movie, or doing other CPU-intensive
things, the results aren't as useful.)
3) Note the results..."
and here are the results w/ xfs mounted:
< Detailed C-state information is only available on Mobile CPUs (laptops) >
2.21 Ghz 0.0%
2.00 Ghz 0.0%
1.80 Ghz 100.0%
Wakeups-from-idle per second : 31.7
no ACPI power usage estimate available
Top causes for wakeups:
37.0% ( 20.0) mount : xfs_mru_cache_create
looks like having this running (note: i'm not using filestreams on this
mounted filesystem) may be impacting the power usage of the CPU? Or
maybe SGI doesn' care about that, if the goal is 100% utilization of
these machines on altixes etc... but still - something to consider I think.