Eric Dumazet wrote:
Furthermore, a lazy sync would mean to change sysctl proc_handler for
"file-nr" to perform a synchronize before calling proc_dointvec, this
would be really obscure.
I was only using your terminology (ie. the 'lazy' synch after the
atomic is updated).
Actually, a better idea would be to make a specific sysctl handler
like Christoph said.
Unless you can show some improvement, it would better not to introduce
the racy hack (even if it is mostly harmless).
Unless the fs people had a problem with that.
And you may as well get rid of the atomic_inc_return which can be more
expensive on some platforms and doesn't buy you much.
atomic_inc;
atomic_read;
Should be enough if you don't care about lost updates here, yeah?
You mean :
atomic_inc(&counter);
lazeyvalue = atomic_read(&counter);
instead of
lazeyvalue = atomic_inc_return(&counter);
Yes.
In fact I couldnt find one architecture where the later would be more
expensive.
atomic_inc_return guarantees a memory barrier, while the former
statements do not. I'm fairly sure it will be more expensive on
a POWER5.
--
SUSE Labs, Novell Inc.
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