On Fri, Mar 24, 2017 at 03:19:47PM -0400, Pavel Tatashin wrote: > Changelog: > v1 - v2 > - Per request, added s390 to deferred "struct page" zeroing > - Collected performance data on x86 which proofs the importance to > keep memset() as prefetch (see below). > > When deferred struct page initialization feature is enabled, we get a > performance gain of initializing vmemmap in parallel after other CPUs are > started. However, we still zero the memory for vmemmap using one boot CPU. > This patch-set fixes the memset-zeroing limitation by deferring it as well. > > Performance gain on SPARC with 32T: > base: https://hastebin.com/ozanelatat.go > fix: https://hastebin.com/utonawukof.go > > As you can see without the fix it takes: 97.89s to boot > With the fix it takes: 46.91 to boot. > > Performance gain on x86 with 1T: > base: https://hastebin.com/uvifasohon.pas > fix: https://hastebin.com/anodiqaguj.pas > > On Intel we save 10.66s/T while on SPARC we save 1.59s/T. Intel has > twice as many pages, and also fewer nodes than SPARC (sparc 32 nodes, vs. > intel 8 nodes). > > It takes one thread 11.25s to zero vmemmap on Intel for 1T, so it should > take additional 11.25 / 8 = 1.4s (this machine has 8 nodes) per node to > initialize the memory, but it takes only additional 0.456s per node, which > means on Intel we also benefit from having memset() and initializing all > other fields in one place. My question was how long it takes if you memset in neither place. -- To unsubscribe from this list: send the line "unsubscribe linux-s390" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
