From 644aa81d1e7ceabc30af950cc268dc00ef74e2af Mon Sep 17 00:00:00 2001 From: Jan Beulich Date: Fri, 27 May 2016 14:48:58 +0200 Subject: [PATCH] x86/PoD: skip eager reclaim when possible Reclaiming pages is pointless when the cache can already satisfy all outstanding PoD entries, and doing reclaims in that case can be very harmful to performance when that memory gets used by the guest, but only to store zeroes there. Signed-off-by: Jan Beulich Reviewed-by: Andrew Cooper Release-acked-by: Wei Liu Reviewed-by: George Dunlap master commit: 556c69f4efb09dd06e6bce4cbb0455287f19d02e master date: 2016-05-12 18:02:21 +0200 --- xen/arch/x86/mm/p2m-pod.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/xen/arch/x86/mm/p2m-pod.c b/xen/arch/x86/mm/p2m-pod.c index b3aa7b1feb..1810eea92d 100644 --- a/xen/arch/x86/mm/p2m-pod.c +++ b/xen/arch/x86/mm/p2m-pod.c @@ -1004,7 +1004,6 @@ static void pod_eager_record(struct p2m_domain *p2m, { struct pod_mrp_list *mrp = &p2m->pod.mrp; - ASSERT(mrp->list[mrp->idx] == INVALID_GFN); ASSERT(gfn != INVALID_GFN); mrp->list[mrp->idx++] = @@ -1052,7 +1051,9 @@ p2m_pod_demand_populate(struct p2m_domain *p2m, unsigned long gfn, return 0; } - pod_eager_reclaim(p2m); + /* Only reclaim if we're in actual need of more cache. */ + if ( p2m->pod.entry_count > p2m->pod.count ) + pod_eager_reclaim(p2m); /* Only sweep if we're actually out of memory. Doing anything else * causes unnecessary time and fragmentation of superpages in the p2m. */