KAMEZAWA Hiroyuki wrote:
But is it too costly that flushing icache page only if a page is newly
installed into the system (PG_arch1) && it is mapped as executable ?
Well it was a bit long time ago, I measured on a Tiger box with
CPUs of 1.3 GHz:
Flushing a page of 64 Kbytes, with modified data in D-cache
(it's slower that not having modified data in the D-cache):
13.1 ... 14.7 usec.
You may have quicker machines, but having more CPUs or a NUMA architecture
can slow it down considerably:
- more CPUs have to agree that that's the moment to carry out a flush
- NUMA adds delay
We may have, say 1 Gbyte / sec local i/o activity (using some RAIDs).
Assume a few % of this 1 Gbyte is the program execution, or program swap in.
It gives some hundreds of new exec pages / sec =>
some msec-s can be lost each sec.
I can agree that it should not be a big deal :-)
I don't want to leak this (stupid) corner case to the file system layer.
Hmm...can't we do clever flushing (like your idea) in VM layer ?
As the VM layer is designed to be independent of the page read in stuff...
Thanks,
Zoltan
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
[Index of Archives]
[Kernel Newbies]
[Netfilter]
[Bugtraq]
[Photo]
[Stuff]
[Gimp]
[Yosemite News]
[MIPS Linux]
[ARM Linux]
[Linux Security]
[Linux RAID]
[Video 4 Linux]
[Linux for the blind]
[Linux Resources]
