Messages in this thread | | | Subject | Re: [PATCH] sched: Change READ_ONCE(jiffies) into jiffies | From | Bart Van Assche <> | Date | Mon, 26 Sep 2016 06:28:38 -0700 |
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On 09/26/16 01:55, Peter Zijlstra wrote: > On Sun, Sep 25, 2016 at 07:08:45PM -0700, Bart Van Assche wrote: >> A quote from Documentation/memory_barriers.txt: >> >> For example, because 'jiffies' is marked volatile, it is never >> necessary to say READ_ONCE(jiffies). The reason for this is >> that READ_ONCE() and WRITE_ONCE() are implemented as volatile >> casts, which has no effect when its argument is already marked >> volatile. >> >> Hence change all 'READ_ONCE(jiffies)' occurrences into 'jiffies'. > > So I'm not a huge fan of this patch. Yes its technically pointless, but > it does convey intent. See the READ_ONCE() as a comment if you will.
Hello Peter,
Are you aware that the scheduler code is the only code that uses READ_ONCE() to read 'jiffies', and that even in the scheduler not all 'jiffies' reads use READ_ONCE()? This patch makes the scheduler code more consistent and easier to read without affecting the generated code.
Bart.
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