Re: [PATCH] removes filp_count_lock and changes nr_files type to atomic_t

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Arjan van de Ven a écrit :
On Thu, 2005-08-25 at 10:45 +0200, Eric Dumazet wrote:

This patch removes filp_count_lock spinlock, used to protect files_stat.nr_files.

Just use atomic_t type and atomic_inc()/atomic_dec() operations.

This patch assumes that atomic_read() is a plain {return v->counter;} on all architectures. (keywords : sysctl, /proc/sys/fs/file-nr, proc_dointvec)



this patch adds atomic ops where there were none before

nope... a spinlock/spinunlock contains atomic ops.

for those architectures that need atomics for read (parisc? arm?)

not today. No atomic needed for read.


however.. wouldn't it be better to make this a per cpu variable for
write, and for read iterate or do something smart otherwise?

So on a machine with 256 CPUS, you want to iterate 256 counters ?
nr_files is not heavily touched, no need to expand it.

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