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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
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11
accel/tcg/translate-all.c
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@ -54,6 +54,7 @@
#include "exec/tb-hash.h"
#include "translate-all.h"
#include "qemu/bitmap.h"
#include "qemu/error-report.h"
#include "qemu/timer.h"
#include "qemu/main-loop.h"
#include "exec/log.h"
@ -112,6 +113,11 @@ typedef struct PageDesc {
#define V_L2_BITS 10
#define V_L2_SIZE (1 << V_L2_BITS)
/* Make sure all possible CPU event bits fit in tb->trace_vcpu_dstate */
QEMU_BUILD_BUG_ON(CPU_TRACE_DSTATE_MAX_EVENTS >
sizeof(((TranslationBlock *)0)->trace_vcpu_dstate)
* BITS_PER_BYTE);
/*
* L1 Mapping properties
*/
@ -1071,7 +1077,7 @@ void tb_phys_invalidate(TranslationBlock *tb, tb_page_addr_t page_addr)
/* remove the TB from the hash list */
phys_pc = tb->page_addr[0] + (tb->pc & ~TARGET_PAGE_MASK);
h = tb_hash_func(phys_pc, tb->pc, tb->flags);
h = tb_hash_func(phys_pc, tb->pc, tb->flags, tb->trace_vcpu_dstate);
qht_remove(&tcg_ctx.tb_ctx.htable, tb, h);
/* remove the TB from the page list */
@ -1216,7 +1222,7 @@ static void tb_link_page(TranslationBlock *tb, tb_page_addr_t phys_pc,
}
/* add in the hash table */
h = tb_hash_func(phys_pc, tb->pc, tb->flags);
h = tb_hash_func(phys_pc, tb->pc, tb->flags, tb->trace_vcpu_dstate);
qht_insert(&tcg_ctx.tb_ctx.htable, tb, h);
#ifdef DEBUG_TB_CHECK
@ -1262,6 +1268,7 @@ TranslationBlock *tb_gen_code(CPUState *cpu,
tb->cs_base = cs_base;
tb->flags = flags;
tb->cflags = cflags;
tb->trace_vcpu_dstate = *cpu->trace_dstate;
tb->invalid = false;
#ifdef CONFIG_PROFILER