22 Feb
2013
22 Feb
'13
2:21 p.m.
On Fri, 2013-02-22 at 15:09 +0100, Peter Zijlstra wrote:
On Fri, 2013-02-22 at 13:50 +0100, Frederic Weisbecker wrote:
Argh!! at what cost? 64bit atomics are like expensive. Wouldn't
adding
a seqlock be saner?
Not sure. This requires a spinlock in the write side which is called from fast path like the timer interrupt.
A single spinlock is _way_ cheaper than a ton of cmpxchg8b()s to update a few variables.
We also have include/linux/u64_stats_sync.h since 2.6.36