[PATCH 3/3] powerpc/mm/nv/hash: Reduce contention on hpte lock
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STALE3016d
From: Aneesh Kumar K.V <hidden>
Date: 2018-06-29 08:36:57
Subsystem:
linux for powerpc (32-bit and 64-bit), the rest · Maintainers:
Madhavan Srinivasan, Linus Torvalds
From: "Aneesh Kumar K.V" <redacted> We do this in some part. This patch make sure we always try to search for hpte without holding lock and redo the compare with lock held once match found. Signed-off-by: Aneesh Kumar K.V <redacted> --- arch/powerpc/mm/hash_native_64.c | 49 +++++++++++++++++++++----------- 1 file changed, 33 insertions(+), 16 deletions(-)
diff --git a/arch/powerpc/mm/hash_native_64.c b/arch/powerpc/mm/hash_native_64.c
index 68e6eaf41bb9..ffbd5ed4e8de 100644
--- a/arch/powerpc/mm/hash_native_64.c
+++ b/arch/powerpc/mm/hash_native_64.c@@ -568,9 +568,19 @@ static void native_hpte_invalidate(unsigned long slot, unsigned long vpn, DBG_LOW(" invalidate(vpn=%016lx, hash: %lx)\n", vpn, slot); want_v = hpte_encode_avpn(vpn, bpsize, ssize); - native_lock_hpte(hptep); hpte_v = hpte_get_old_v(hptep); + if (HPTE_V_COMPARE(hpte_v, want_v) && (hpte_v & HPTE_V_VALID)) { + native_lock_hpte(hptep); + /* recheck with locks held */ + hpte_v = hpte_get_old_v(hptep); + + if (HPTE_V_COMPARE(hpte_v, want_v) && (hpte_v & HPTE_V_VALID)) + /* Invalidate the hpte. NOTE: this also unlocks it */ + hptep->v = 0; + else + native_unlock_hpte(hptep); + } /* * We need to invalidate the TLB always because hpte_remove doesn't do * a tlb invalidate. If a hash bucket gets full, we "evict" a more/less
@@ -578,13 +588,6 @@ static void native_hpte_invalidate(unsigned long slot, unsigned long vpn, * (hpte_remove) because we assume the old translation is still * technically "valid". */ - if (!HPTE_V_COMPARE(hpte_v, want_v) || !(hpte_v & HPTE_V_VALID)) - native_unlock_hpte(hptep); - else - /* Invalidate the hpte. NOTE: this also unlocks it */ - hptep->v = 0; - - /* Invalidate the TLB */ tlbie(vpn, bpsize, apsize, ssize, local); local_irq_restore(flags);
@@ -626,15 +629,23 @@ static void native_hugepage_invalidate(unsigned long vsid, hptep = htab_address + slot; want_v = hpte_encode_avpn(vpn, psize, ssize); - native_lock_hpte(hptep); hpte_v = hpte_get_old_v(hptep); /* Even if we miss, we need to invalidate the TLB */ - if (!HPTE_V_COMPARE(hpte_v, want_v) || !(hpte_v & HPTE_V_VALID)) - native_unlock_hpte(hptep); - else - /* Invalidate the hpte. NOTE: this also unlocks it */ - hptep->v = 0; + if (HPTE_V_COMPARE(hpte_v, want_v) && (hpte_v & HPTE_V_VALID)) { + /* recheck with locks held */ + native_lock_hpte(hptep); + hpte_v = hpte_get_old_v(hptep); + + if (HPTE_V_COMPARE(hpte_v, want_v) && (hpte_v & HPTE_V_VALID)) { + /* + * Invalidate the hpte. NOTE: this also unlocks it + */ + + hptep->v = 0; + } else + native_unlock_hpte(hptep); + } /* * We need to do tlb invalidate for all the address, tlbie * instruction compares entry_VA in tlb with the VA specified
@@ -802,13 +813,19 @@ static void native_flush_hash_range(unsigned long number, int local) slot += hidx & _PTEIDX_GROUP_IX; hptep = htab_address + slot; want_v = hpte_encode_avpn(vpn, psize, ssize); + hpte_v = hpte_get_old_v(hptep); + + if (!HPTE_V_COMPARE(hpte_v, want_v) || !(hpte_v & HPTE_V_VALID)) + continue; + /* lock and try again */ native_lock_hpte(hptep); hpte_v = hpte_get_old_v(hptep); - if (!HPTE_V_COMPARE(hpte_v, want_v) || - !(hpte_v & HPTE_V_VALID)) + + if (!HPTE_V_COMPARE(hpte_v, want_v) || !(hpte_v & HPTE_V_VALID)) native_unlock_hpte(hptep); else hptep->v = 0; + } pte_iterate_hashed_end(); }
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2.17.1