[Xen-ia64-devel] [PATCH 0/10] [RFC] performance tuning TAKE 3

[Isaku Yamahata <yamahata@xxxxxxxxxxxxx>]

Hi all
These patches are for performance tuning TAKE 3.
They are for comment, review and evaluation.

PATCHES:
- performace counter
  NEW
- per vcpu vhpt
- tlb tracking
- deferred page freeing
- p2m exposure
  NEW

CHANGES:
- various bug fixes.
  especially deferred page freeing patch bug.
  It spoiled performance much.

- performance counter
  added performance counter.
  I added these for evaluation of the patches.
  But I think some of them are usefull for normal use.
  Is there any objection for commit?

- P2M table exposure
  I also included test module for p2m exposure module.
  It showed that p2m conversion with p2m exposure is faster than
  the hypercall conversion at about order 2.
  So I think p2m exposure patch is acceptable.


PATCH DETAIL:
- per vcpu vhpt
  It focuses on vcpu migration between physical cpus.
  With credit scheduler, vcpu is heavily migrated.
  This patch tries to reduce vTLB flush when vcpu is migrated.

- tlb tracking
  It forcuses on grant table mapping.
  When page is unmapped, full vTLB flush is necessary.
  By tracking tlb insert on grant mapped page, full vTLB flush
  can be avoided.
  Especially vbd does only DMA, so dom0 doesn't insert tlb entry
  on the grant mapped page. In such case any vTLB flush isn't needed.

- deferred page freeing
  When the page in which tlb insert isn't tracked is unmapped/zapped from
  domain, full vTLB flush is necessary again.
  Balloon driver and grant table page transfer is the case.
  This patch focuses on it.
  It tries to batch freeing/zapping page from domain in order
  to reduce full vTLB flush.

- p2m exposure
  DMA paravirtualization requires the conversion from pseudo physical address
  to machine address. Currently it is done by hypercall.
  This patch tries to reduce the conversion overhead by read-only 
  mapping the xen p2m table to domain.


thanks.

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