http://bugzilla.suse.com/show_bug.cgi?id=1127808
http://bugzilla.suse.com/show_bug.cgi?id=1127808#c7
--- Comment #7 from Mel Gorman
We are switching to SLUB, so we can reconsider enabling SLAB_FREELIST_HARDENED.
tldr: enable it for master and SLE 15 SP2. I think it's ok to enable this option based on the preliminary results but it's borderline at parts. The upstream report that the headline performance impact is minimal and that is correct but in some cases the results is more variable. The *average* performance is fine but the outliers are larger. Consider this slab-intensive workload on UMA for example http://laplace.suse.de/evaluations/SLE-15-SP2/0002-sec-hardened-freelist/net... Note that the Hmean (harmonic mean) is barely changed but look at the stddev figures like "Stddev send-2048" as an example. Relatively speaking it's much larger. This in itself as the coefficient of variance shows that while it might be more variable in absoulte terms, it's not much more in relative terms (varying by 0.93% instead of 0.41%). Because the variance increase is small in relative terms, I'm not too concerned. It's also possible that this is simply a co-incidence as FREELIST_HARDENED does not do that much real work as such. The vast majority of workloads tested show marginal to no difference. While some large regressions were reported, they were on NUMA machines for workloads that occasionally suffer from scheduler decisions (to be researched) and is *not* related to FREELIST_HARDENED. On that basis, I think it's safe to enable but we'll keep an eye on it just in case. -- You are receiving this mail because: You are on the CC list for the bug.