Re: [PATCH] removes filp_count_lock and changes nr_files type toatomic_t
From: Eric Dumazet
Date: Thu Aug 25 2005 - 10:13:40 EST
Nick Piggin a écrit :
OK, well I would prefer you do the proper atomic operations throughout
where it "really matters" in file_table.c, and do your lazy synchronize
with just the sysctl exported value.
But... I got complains about atomic_read(&counter) being 'an atomic op'
(untrue), so my second patch just doesnt touch the path where nr_files was read.
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.
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);
In fact I couldnt find one architecture where the later would be more expensive.
Nick
Eric
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