On Thu, 29 Nov 2007 12:05:13 -0700 Matthew Wilcox <[EMAIL PROTECTED]> wrote:
> The database performance group have found that half the cycles spent > in kmem_cache_free are spent in this one call to BUG_ON. Moving it > into the CONFIG_SLAB_DEBUG-only function cache_free_debugcheck() is a > performance win of almost 0.5% on their particular benchmark. > > The call was added as part of commit ddc2e812d592457747c4367fb73edcaa8e1e49ff > with the comment that "overhead should be minimal". It may have been > minimal at the time, but it isn't now. > It is worth noting that the offending commit hit mainline in June 2006. It takes a very long time for some performance regressions to be discovered. By which time it is effectively too late to fix it. - 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/
