[email protected] wrote:
On Sun, 5 Aug 2007, Diego Calleja wrote:
El Sun, 5 Aug 2007 09:13:20 +0200, Ingo Molnar <[email protected]> escribió:
Measurements show that noatime helps 20-30% on regular desktop
workloads, easily 50% for kernel builds and much more than that (in
excess of 100%) for file-read-intense workloads. We cannot just walk
And as everybody knows in servers is a popular practice to disable it.
According to an interview to the kernel.org admins....
"Beyond that, Peter noted, "very little fancy is going on, and that is
good
because fancy is hard to maintain." He explained that the only fancy
thing
being done is that all filesystems are mounted noatime meaning that the
system doesn't have to make writes to the filesystem for files which are
simply being read, "that cut the load average in half."
I bet that some people would consider such performance hit a bug...
actually, it's popular practice to disable it by people who know how big
a hit it is and know how few programs use it.
i've been a linux sysadmin for 10 years, and have known about noatime
for at least 7 years, but I always thought of it in the catagory of 'use
it only on your performance critical machines where you are trying to
extract every ounce of performance, and keep an eye out for things
misbehaving'
I never imagined that itwas the 20%+ hit that is being described, and
with so little impact, or I would have switched to it across the board
years ago.
To get that magnitude you need slow disk with very fast CPU. It helps
most of systems where the disk hardware is marginal or worse for the i/o
load. Don't take that as typical.
I'll bet there are a lot of admins out there in the same boat.
adding an option in the kernel to change the default sounds like a very
good first step, even if the default isn't changed today.
--
Bill Davidsen <[email protected]>
"We have more to fear from the bungling of the incompetent than from
the machinations of the wicked." - from Slashdot
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