97 lines
3.5 KiB
Diff
97 lines
3.5 KiB
Diff
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From 603d882c9c1c61475a69f657a9550bb335bf3ca9 Mon Sep 17 00:00:00 2001
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From: Ulrich Hecht <uli@suse.de>
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Date: Wed, 22 Jul 2009 14:03:19 +0200
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Subject: [PATCH 25/33] linux-user: don't do locking in single-threaded processes
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Skips setting the tb_lock if a process doesn't have more than one thread,
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which is usually the case. Results in about 20% performance gain (measured
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with the s390x target, but the effect should be similar with other targets).
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Signed-off-by: Ulrich Hecht <uli@suse.de>
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---
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cpu-defs.h | 8 ++++++++
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cpu-exec.c | 14 ++++++++++++--
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linux-user/syscall.c | 1 +
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3 files changed, 21 insertions(+), 2 deletions(-)
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diff --git a/cpu-defs.h b/cpu-defs.h
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index d73ec0a..27e5bb2 100644
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--- a/cpu-defs.h
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+++ b/cpu-defs.h
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@@ -135,6 +135,13 @@ typedef struct CPUWatchpoint {
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} CPUWatchpoint;
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#define CPU_TEMP_BUF_NLONGS 128
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+
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+#ifdef CONFIG_USER_ONLY
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+#define MULTITHREAD uint32_t multithreaded;
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+#else
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+#define MULTITHREAD
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+#endif
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+
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#define CPU_COMMON \
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struct TranslationBlock *current_tb; /* currently executing TB */ \
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/* soft mmu support */ \
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@@ -149,6 +156,7 @@ typedef struct CPUWatchpoint {
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uint32_t stop; /* Stop request */ \
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uint32_t stopped; /* Artificially stopped */ \
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uint32_t interrupt_request; \
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+ MULTITHREAD /* needs locking when accessing TBs */ \
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volatile sig_atomic_t exit_request; \
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/* The meaning of the MMU modes is defined in the target code. */ \
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CPUTLBEntry tlb_table[NB_MMU_MODES][CPU_TLB_SIZE]; \
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diff --git a/cpu-exec.c b/cpu-exec.c
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index 855ea3e..1371ce4 100644
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--- a/cpu-exec.c
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+++ b/cpu-exec.c
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@@ -219,6 +219,9 @@ int cpu_exec(CPUState *env1)
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TranslationBlock *tb;
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uint8_t *tc_ptr;
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unsigned long next_tb;
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+#ifdef CONFIG_USER_ONLY
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+ uint32_t multithreaded;
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+#endif
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if (cpu_halted(env1) == EXCP_HALTED)
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return EXCP_HALTED;
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@@ -604,7 +607,11 @@ int cpu_exec(CPUState *env1)
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#endif
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}
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#endif
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- spin_lock(&tb_lock);
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+#ifdef CONFIG_USER_ONLY
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+ multithreaded = env->multithreaded;
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+ if (multithreaded)
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+#endif
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+ spin_lock(&tb_lock);
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tb = tb_find_fast();
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/* Note: we do it here to avoid a gcc bug on Mac OS X when
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doing it in tb_find_slow */
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@@ -632,7 +639,10 @@ int cpu_exec(CPUState *env1)
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tb_add_jump((TranslationBlock *)(next_tb & ~3), next_tb & 3, tb);
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}
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}
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- spin_unlock(&tb_lock);
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+#ifdef CONFIG_USER_ONLY
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+ if (multithreaded)
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+#endif
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+ spin_unlock(&tb_lock);
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env->current_tb = tb;
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/* cpu_interrupt might be called while translating the
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diff --git a/linux-user/syscall.c b/linux-user/syscall.c
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index e9b07df..f7a411d 100644
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--- a/linux-user/syscall.c
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+++ b/linux-user/syscall.c
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@@ -3560,6 +3560,7 @@ static int do_fork(CPUState *env, unsigned int flags, abi_ulong newsp,
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ts = qemu_mallocz(sizeof(TaskState) + NEW_STACK_SIZE);
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init_task_state(ts);
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new_stack = ts->stack;
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+ env->multithreaded = 1;
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/* we create a new CPU instance. */
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new_env = cpu_copy(env);
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/* Init regs that differ from the parent. */
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--
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1.6.2.1
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