On Fri, Mar 24, 2017 at 09:51:09AM +0100, Christian Borntraeger wrote: > On 03/24/2017 12:01 AM, Pavel Tatashin wrote: > > 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. > > > > Here is example 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. > > > > On x86 time saving is going to be even greater (proportionally to memory size) > > because there are twice as many "struct page"es for the same amount of memory, > > as base pages are twice smaller. > > Fixing the linux-s390 mailing list email. > This might be useful for s390 as well. Unfortunately only for the fake numa case, since as far as I understand it, parallelization happens only on a node granularity. And since we are usually only having one node... But anyway, it won't hurt to set ARCH_SUPPORTS_DEFERRED_STRUCT_PAGE_INIT on s390 also. I'll do some testing and then we'll see. Pavel, could you please change your patch 5 so it also converts the s390 call sites of vmemmap_alloc_block() so they use VMEMMAP_ZERO instead of 'true' as argument? -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>
