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[Qemu-devel] [PATCH v3 29/43] translate-all: report correct avg host TB
From: |
Emilio G. Cota |
Subject: |
[Qemu-devel] [PATCH v3 29/43] translate-all: report correct avg host TB size |
Date: |
Wed, 19 Jul 2017 23:09:15 -0400 |
Since commit 6e3b2bfd6 ("tcg: allocate TB structs before the
corresponding translated code") we are not fully utilizing
code_gen_buffer for translated code, and therefore are
incorrectly reporting the amount of translated code as well as
the average host TB size. Address this by:
- Making the conscious choice of misreporting the total translated code;
doing otherwise would mislead users into thinking "-tb-size" is not
honoured.
- Expanding tb_tree_stats to accurately count the bytes of translated code on
the host, and using this for reporting the average tb host size,
as well as the expansion ratio.
In the future we might want to consider reporting the accurate numbers for
the total translated code, together with a "bookkeeping/overhead" field to
account for the TB structs.
Reviewed-by: Richard Henderson <address@hidden>
Signed-off-by: Emilio G. Cota <address@hidden>
---
accel/tcg/translate-all.c | 32 +++++++++++++++++++++++---------
1 file changed, 23 insertions(+), 9 deletions(-)
diff --git a/accel/tcg/translate-all.c b/accel/tcg/translate-all.c
index 448f13b..d50e2b9 100644
--- a/accel/tcg/translate-all.c
+++ b/accel/tcg/translate-all.c
@@ -923,6 +923,15 @@ static void page_flush_tb(void)
}
}
+static gboolean tb_host_size_iter(gpointer key, gpointer value, gpointer data)
+{
+ const TranslationBlock *tb = value;
+ size_t *size = data;
+
+ *size += tb->tc.size;
+ return false;
+}
+
/* flush all the translation blocks */
static void do_tb_flush(CPUState *cpu, run_on_cpu_data tb_flush_count)
{
@@ -937,11 +946,12 @@ static void do_tb_flush(CPUState *cpu, run_on_cpu_data
tb_flush_count)
if (DEBUG_TB_FLUSH_GATE) {
size_t nb_tbs = g_tree_nnodes(tcg_ctx.tb_ctx.tb_tree);
+ size_t host_size = 0;
- printf("qemu: flush code_size=%td nb_tbs=%zu avg_tb_size=%td\n",
+ g_tree_foreach(tcg_ctx.tb_ctx.tb_tree, tb_host_size_iter, &host_size);
+ printf("qemu: flush code_size=%td nb_tbs=%zu avg_tb_size=%zu\n",
tcg_ctx.code_gen_ptr - tcg_ctx.code_gen_buffer, nb_tbs,
- nb_tbs > 0 ?
- (tcg_ctx.code_gen_ptr - tcg_ctx.code_gen_buffer) / nb_tbs : 0);
+ nb_tbs > 0 ? host_size / nb_tbs : 0);
}
if ((unsigned long)(tcg_ctx.code_gen_ptr - tcg_ctx.code_gen_buffer)
> tcg_ctx.code_gen_buffer_size) {
@@ -1883,6 +1893,7 @@ static void print_qht_statistics(FILE *f,
fprintf_function cpu_fprintf,
}
struct tb_tree_stats {
+ size_t host_size;
size_t target_size;
size_t max_target_size;
size_t direct_jmp_count;
@@ -1895,6 +1906,7 @@ static gboolean tb_tree_stats_iter(gpointer key, gpointer
value, gpointer data)
const TranslationBlock *tb = value;
struct tb_tree_stats *tst = data;
+ tst->host_size += tb->tc.size;
tst->target_size += tb->size;
if (tb->size > tst->max_target_size) {
tst->max_target_size = tb->size;
@@ -1923,6 +1935,11 @@ void dump_exec_info(FILE *f, fprintf_function
cpu_fprintf)
g_tree_foreach(tcg_ctx.tb_ctx.tb_tree, tb_tree_stats_iter, &tst);
/* XXX: avoid using doubles ? */
cpu_fprintf(f, "Translation buffer state:\n");
+ /*
+ * Report total code size including the padding and TB structs;
+ * otherwise users might think "-tb-size" is not honoured.
+ * For avg host size we use the precise numbers from tb_tree_stats though.
+ */
cpu_fprintf(f, "gen code size %td/%zd\n",
tcg_ctx.code_gen_ptr - tcg_ctx.code_gen_buffer,
tcg_ctx.code_gen_highwater - tcg_ctx.code_gen_buffer);
@@ -1930,12 +1947,9 @@ void dump_exec_info(FILE *f, fprintf_function
cpu_fprintf)
cpu_fprintf(f, "TB avg target size %zu max=%zu bytes\n",
nb_tbs ? tst.target_size / nb_tbs : 0,
tst.max_target_size);
- cpu_fprintf(f, "TB avg host size %td bytes (expansion ratio: %0.1f)\n",
- nb_tbs ? (tcg_ctx.code_gen_ptr -
- tcg_ctx.code_gen_buffer) / nb_tbs : 0,
- tst.target_size ? (double) (tcg_ctx.code_gen_ptr -
- tcg_ctx.code_gen_buffer) /
- tst.target_size : 0);
+ cpu_fprintf(f, "TB avg host size %zu bytes (expansion ratio: %0.1f)\n",
+ nb_tbs ? tst.host_size / nb_tbs : 0,
+ tst.target_size ? (double)tst.host_size / tst.target_size : 0);
cpu_fprintf(f, "cross page TB count %zu (%zu%%)\n", tst.cross_page,
nb_tbs ? (tst.cross_page * 100) / nb_tbs : 0);
cpu_fprintf(f, "direct jump count %zu (%zu%%) (2 jumps=%zu %zu%%)\n",
--
2.7.4
- [Qemu-devel] [PATCH v3 07/43] tcg/mips: constify tcg_target_callee_save_regs, (continued)
- [Qemu-devel] [PATCH v3 07/43] tcg/mips: constify tcg_target_callee_save_regs, Emilio G. Cota, 2017/07/19
- [Qemu-devel] [PATCH v3 15/43] target/i386: check CF_PARALLEL instead of parallel_cpus, Emilio G. Cota, 2017/07/19
- [Qemu-devel] [PATCH v3 08/43] tcg: remove addr argument from lookup_tb_ptr, Emilio G. Cota, 2017/07/19
- [Qemu-devel] [PATCH v3 06/43] tcg/i386: constify tcg_target_callee_save_regs, Emilio G. Cota, 2017/07/19
- [Qemu-devel] [PATCH v3 01/43] cputlb: bring back tlb_flush_count under !TLB_DEBUG, Emilio G. Cota, 2017/07/19
- [Qemu-devel] [PATCH v3 16/43] target/m68k: check CF_PARALLEL instead of parallel_cpus, Emilio G. Cota, 2017/07/19
- [Qemu-devel] [PATCH v3 19/43] target/sparc: check CF_PARALLEL instead of parallel_cpus, Emilio G. Cota, 2017/07/19
- [Qemu-devel] [PATCH v3 22/43] translate-all: define and use DEBUG_TB_FLUSH_GATE, Emilio G. Cota, 2017/07/19
- [Qemu-devel] [PATCH v3 32/43] tcg: take .helpers out of TCGContext, Emilio G. Cota, 2017/07/19
- [Qemu-devel] [PATCH v3 29/43] translate-all: report correct avg host TB size,
Emilio G. Cota <=
- [Qemu-devel] [PATCH v3 25/43] translate-all: define and use DEBUG_TB_CHECK_GATE, Emilio G. Cota, 2017/07/19
- [Qemu-devel] [PATCH v3 24/43] translate-all: define and use DEBUG_TB_INVALIDATE_GATE, Emilio G. Cota, 2017/07/19
- [Qemu-devel] [PATCH v3 02/43] tcg: fix corruption of code_time profiling counter upon tb_flush, Emilio G. Cota, 2017/07/19
- [Qemu-devel] [PATCH v3 28/43] exec-all: rename tb_free to tb_remove, Emilio G. Cota, 2017/07/19
- [Qemu-devel] [PATCH v3 23/43] exec-all: introduce TB_PAGE_ADDR_FMT, Emilio G. Cota, 2017/07/19
- [Qemu-devel] [PATCH v3 26/43] exec-all: extract tb->tc_* into a separate struct tc_tb, Emilio G. Cota, 2017/07/19
- [Qemu-devel] [PATCH v3 17/43] target/s390x: check CF_PARALLEL instead of parallel_cpus, Emilio G. Cota, 2017/07/19
- [Qemu-devel] [PATCH v3 34/43] gen-icount: fold exitreq_label into TCGContext, Emilio G. Cota, 2017/07/19
- [Qemu-devel] [PATCH v3 09/43] tcg: consolidate TB lookups in tb_lookup__cpu_state, Emilio G. Cota, 2017/07/19