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[Qemu-devel] [PATCH 01/13] cputlb: do not evict empty entries to the vtl
From: |
Richard Henderson |
Subject: |
[Qemu-devel] [PATCH 01/13] cputlb: do not evict empty entries to the vtlb |
Date: |
Wed, 23 Jan 2019 14:56:53 -0800 |
From: "Emilio G. Cota" <address@hidden>
Currently we evict an entry to the victim TLB when it doesn't match
the current address. But it could be that there's no match because
the current entry is empty (i.e. all -1's, for instance via tlb_flush).
Do not evict the entry to the vtlb in that case.
This change will help us keep track of the TLB's use rate, which
we'll use to implement a policy for dynamic TLB sizing.
Tested-by: Alex Bennée <address@hidden>
Reviewed-by: Alex Bennée <address@hidden>
Reviewed-by: Richard Henderson <address@hidden>
Signed-off-by: Emilio G. Cota <address@hidden>
Message-Id: <address@hidden>
Signed-off-by: Richard Henderson <address@hidden>
---
accel/tcg/cputlb.c | 11 ++++++++++-
1 file changed, 10 insertions(+), 1 deletion(-)
diff --git a/accel/tcg/cputlb.c b/accel/tcg/cputlb.c
index af6bd8ccf9..10f1150c62 100644
--- a/accel/tcg/cputlb.c
+++ b/accel/tcg/cputlb.c
@@ -224,6 +224,15 @@ static inline bool tlb_hit_page_anyprot(CPUTLBEntry
*tlb_entry,
tlb_hit_page(tlb_entry->addr_code, page);
}
+/**
+ * tlb_entry_is_empty - return true if the entry is not in use
+ * @te: pointer to CPUTLBEntry
+ */
+static inline bool tlb_entry_is_empty(const CPUTLBEntry *te)
+{
+ return te->addr_read == -1 && te->addr_write == -1 && te->addr_code == -1;
+}
+
/* Called with tlb_c.lock held */
static inline void tlb_flush_entry_locked(CPUTLBEntry *tlb_entry,
target_ulong page)
@@ -591,7 +600,7 @@ void tlb_set_page_with_attrs(CPUState *cpu, target_ulong
vaddr,
* Only evict the old entry to the victim tlb if it's for a
* different page; otherwise just overwrite the stale data.
*/
- if (!tlb_hit_page_anyprot(te, vaddr_page)) {
+ if (!tlb_hit_page_anyprot(te, vaddr_page) && !tlb_entry_is_empty(te)) {
unsigned vidx = env->tlb_d[mmu_idx].vindex++ % CPU_VTLB_SIZE;
CPUTLBEntry *tv = &env->tlb_v_table[mmu_idx][vidx];
--
2.17.2
- [Qemu-devel] [PATCH 00/13] Dynamic TLB sizing, backends, Richard Henderson, 2019/01/23
- [Qemu-devel] [PATCH 01/13] cputlb: do not evict empty entries to the vtlb,
Richard Henderson <=
- [Qemu-devel] [PATCH 02/13] tcg: introduce dynamic TLB sizing, Richard Henderson, 2019/01/23
- [Qemu-devel] [PATCH 03/13] tcg/i386: enable dynamic TLB sizing, Richard Henderson, 2019/01/23
- [Qemu-devel] [PATCH 06/13] tcg/sparc: enable dynamic TLB sizing, Richard Henderson, 2019/01/23
- [Qemu-devel] [PATCH 04/13] tcg/aarch64: enable dynamic TLB sizing, Richard Henderson, 2019/01/23
- [Qemu-devel] [PATCH 12/13] tcg/tci: enable dynamic TLB sizing, Richard Henderson, 2019/01/23
- [Qemu-devel] [PATCH 05/13] tcg/ppc: enable dynamic TLB sizing, Richard Henderson, 2019/01/23
- [Qemu-devel] [PATCH 10/13] tcg/mips: Fix tcg_out_qemu_ld_slow_path, Richard Henderson, 2019/01/23
- [Qemu-devel] [PATCH 11/13] tcg/mips: enable dynamic TLB sizing, Richard Henderson, 2019/01/23