From: Matthew Wilcox <willy@xxxxxxxxxxxxx> Date: Thu, 23 Mar 2017 16:26:38 -0700 > On Thu, Mar 23, 2017 at 07:01:48PM -0400, 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. > > How long does it take if we just don't zero this memory at all? We seem > to be initialising most of struct page in __init_single_page(), so it > seems like a lot of additional complexity to conditionally zero the rest > of struct page. Alternatively, just zero out the entire vmemmap area when it is setup in the kernel page tables. -- 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>
