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exec: [tcg] Use different TBs according to the vCPU's dynamic tracing state

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Every vCPU now uses a separate set of TBs for each set of dynamic
tracing event state values. Each set of TBs can be used by any number of
vCPUs to maximize TB reuse when vCPUs have the same tracing state.

This feature is later used by tracetool to optimize tracing of guest
code events.

The maximum number of TB sets is defined as 2^E, where E is the number
of events that have the 'vcpu' property (their state is stored in
CPUState->trace_dstate).

For this to work, a change on the dynamic tracing state of a vCPU will
force it to flush its virtual TB cache (which is only indexed by
address), and fall back to the physical TB cache (which now contains the
vCPU's dynamic tracing state as part of the hashing function).

Signed-off-by: Lluís Vilanova <vilanova@ac.upc.edu>
Reviewed-by: Richard Henderson <rth@twiddle.net>
Reviewed-by: Emilio G. Cota <cota@braap.org>
Signed-off-by: Emilio G. Cota <cota@braap.org>
Message-id: 149915775266.6295.10060144081246467690.stgit@frigg.lan
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
This commit is contained in:
Lluís Vilanova 2017-07-04 10:42:32 +02:00 • committed by Stefan Hajnoczi
parent d43811165d
commit 61a67f71dd
9 changed files with 33 additions and 10 deletions
Download patch file Download diff file Expand all files Collapse all files

7
include/exec/tb-hash-xx.h
View file

@ -49,7 +49,7 @@
* contiguous in memory.
*/
static inline
uint32_t tb_hash_func5(uint64_t a0, uint64_t b0, uint32_t e)
uint32_t tb_hash_func6(uint64_t a0, uint64_t b0, uint32_t e, uint32_t f)
{
uint32_t v1 = TB_HASH_XX_SEED + PRIME32_1 + PRIME32_2;
uint32_t v2 = TB_HASH_XX_SEED + PRIME32_2;
@ -78,11 +78,14 @@ uint32_t tb_hash_func5(uint64_t a0, uint64_t b0, uint32_t e)
v4 *= PRIME32_1;
h32 = rol32(v1, 1) + rol32(v2, 7) + rol32(v3, 12) + rol32(v4, 18);
h32 += 20;
h32 += 24;
h32 += e * PRIME32_3;
h32 = rol32(h32, 17) * PRIME32_4;
h32 += f * PRIME32_3;
h32 = rol32(h32, 17) * PRIME32_4;
h32 ^= h32 >> 15;
h32 *= PRIME32_2;
h32 ^= h32 >> 13;