[v3 0/9] parallelized "struct page" zeroing

From: Pavel Tatashin
Date: Fri May 05 2017 - 13:04:59 EST

v2 - v3
- Addressed David's comments about one change per patch:
* Splited changes to platforms into 4 patches
* Made "do not zero vmemmap_buf" as a separate patch
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.

Pavel Tatashin (9):
sparc64: simplify vmemmap_populate
mm: defining memblock_virt_alloc_try_nid_raw
mm: add "zero" argument to vmemmap allocators
mm: do not zero vmemmap_buf
mm: zero struct pages during initialization
sparc64: teach sparc not to zero struct pages memory
x86: teach x86 not to zero struct pages memory
powerpc: teach platforms not to zero struct pages memory
s390: teach platforms not to zero struct pages memory

arch/powerpc/mm/init_64.c | 4 +-
arch/s390/mm/vmem.c | 5 ++-
arch/sparc/mm/init_64.c | 26 +++++++----------------
arch/x86/mm/init_64.c | 3 +-
include/linux/bootmem.h | 3 ++
include/linux/mm.h | 15 +++++++++++--
mm/memblock.c | 46 ++++++++++++++++++++++++++++++++++++------
mm/page_alloc.c | 3 ++
mm/sparse-vmemmap.c | 48 +++++++++++++++++++++++++++++---------------
9 files changed, 103 insertions(+), 50 deletions(-)