On 11/13/2013 01:14 AM, Yuanhan Liu wrote:
> Hi,
>
> FYI, we found some performance regressions caused by commit 1ca7d67c
> ("seqcount: Add lockdep functionality to seqcount/seqlock structures")So this is expected. seqlock readers are usually very very cheap operations, and we're now doing lockdep tracking on every iteration around the loop. As the lockdep help states: | If you say Y here, the lock dependency engine will do | | additional runtime checks to debug itself, at the price | | of more runtime overhead. So now since we're also tracking seqlocks in addition to spinlocks, it creates more overhead. Disabling CONFIG_LOCKDEP should restore performance. thanks -john -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
