From: Richard Henderson <rth@twiddle.net>
To: qemu-devel@nongnu.org
Cc: peter.maydell@linaro.org, "Emilio G. Cota" <cota@braap.org>
Subject: [Qemu-devel] [PULL 11/26] tb-hash: improve tb_jmp_cache hash function in user mode
Date: Mon, 5 Jun 2017 09:52:18 -0700 [thread overview]
Message-ID: <20170605165233.4135-12-rth@twiddle.net> (raw)
In-Reply-To: <20170605165233.4135-1-rth@twiddle.net>
From: "Emilio G. Cota" <cota@braap.org>
Optimizations to cross-page chaining and indirect branches make
performance more sensitive to the hit rate of tb_jmp_cache.
The constraint of reserving some bits for the page number
lowers the achievable quality of the hashing function.
However, user-mode does not have this requirement. Thus,
with this change we use for user-mode a hashing function that
is both faster and of better quality than the previous one.
Measurements:
Note: baseline (i.e. speedup == 1x) is QEMU v2.9.0.
- SPECint06 (test set), x86_64-linux-user. Host: Intel i7-6700K @ 4.00GHz
2.2x +-+--------------------------------------------------------------------------------------------------------------+-+
| |
| jr |
2x +jr+multhash +....................................................+++++...................................+-+
| jr+hash |$$$ |
| |$+$ |
| ### $ |
1.8x +-+......................................................................#|#.$...................................+-+
| ++#+# $ |
| |# # $ |
1.6x +-+....................................................................***.#.$....................++$$$..........+-+
| $$$ *+* # $ |$+$ |
| ++$$$ ### $ * * # $ +++|$ $ |
| ++###+$ # # $ * * # $ ### ****## $ |
1.4x +-+...................***+#.$.........***.#.$..........................*.*.#.$...........#+#$$.*++*|#.$..........+-+
| *+* # $ * * # $ * * # $ # # $ * *+# $ |
| * * # $ +++++ * * # $ * * # $ *** # $ * * # $ ###$$ |
1.2x +-+...................*.*.#.$.***##$$.*.*.#.$..........................*.*.#.$.........*.*.#.$.*..*.#.$.***+#+$..+-+
| * * # $ *+* # $ * * # $ +++ * * # $ ++###$$ * * # $ * * # $ * * # $ |
| ***##$$ * * # $ * * # $ * * # $ ***##$$ ++### * * # $ *** #+$ * * # $ * * # $ * * # $ |
| *+*+#+$ ***##$$$ * * # $ * * # $ * * # $ *+* # $ ++####$$ ***+# * * # $ * * # $ * * # $ * * # $ * * # $ |
1x +-++-*+*+#+$+*+*+#-+$+*+*-#+$+*+*+#+$+*+*+#+$+*-*+#+$+***++#+$+*+*+#$$+*+*+#+$+*+*+#+$+*+*-#+$+*+-*+#+$+*+*+#+$-++-+
| * * # $ * * # $ * * # $ * * # $ * * # $ * * # $ * * # $ * * # $ * * # $ * * # $ * * # $ * * # $ * * # $ |
| * * # $ * * # $ * * # $ * * # $ * * # $ * * # $ * * # $ * * # $ * * # $ * * # $ * * # $ * * # $ * * # $ |
0.8x +-+--***##$$-***##$$$-***##$$-***##$$-***##$$-***##$$-***###$$-***##$$-***##$$-***##$$-***##$$-****##$$-***##$$--+-+
astar bzip2 gcc gobmk h264ref hmmlibquantum mcf omnetpperlbench sjengxalancbmk hmean
png: http://imgur.com/4UXTrEc
Here I also tried the hash function suggested by Paolo ("multhash"):
return ((uint64_t) (pc * 2654435761) >> 32) & (TB_JMP_CACHE_SIZE - 1);
As you can see it is just as good as the other new function ("hash"),
which is what I ended up going with.
- SPECint06 (train set), x86_64-linux-user. Host: Intel i7-6700K @ 4.00GHz
2.6x +-+--------------------------------------------------------------------------------------------------------------+-+
| |
| jr ### |
2.4x +jr+hash...........................................................................................#.#...........+-+
| # # |
| # # |
2.2x +-+................................................................................................#.#...........+-+
| # # |
| # # |
2x +-+................................................................................................#.#...........+-+
| **** # |
| * * # |
1.8x +-+.............................................................................................*..*.#...........+-+
| +++ * * # |
| #### #### * * # |
1.6x +-+......................................####.............................#..#.****..#..........*..*.#...........+-+
| +++ #++# **** # * * # #### * * # |
| ### # # * * # * * # # # * * # |
1.4x +-+...................****+#..........****..#..........................*..*..#.*..*..#....#..#..*..*.#...........+-+
| *++* # * * # * * # * * # *** # * * # #### |
| * * # #### * * # * * # * * # * * # * * # **** # |
1.2x +-+...................*..*.#..****++#.*..*..#..........................*..*..#.*..*..#..*.*..#..*..*.#..*..*..#..+-+
| ****### * * # * * # * * # * * # * * # * * # * * # * * # |
| * * # ***### * * # * * # * * # ****## * * # * * # * * # * * # * * # |
1x +-+--****###--***###--****##--****###-****###--***###--***###--****##--****###-****###--***###--****##--****###--+-+
astar bzip2 gcc gobmk h264ref hmmlibquantum mcf omnetpperlbench sjengxalancbmk hmean
png: http://imgur.com/ArCbHqo
- NBench, x86_64-linux-user. Host: Intel i7-6700K @ 4.00GHz
1.12x +-+-------------------------------------------------------------------------------------------------------------+-+
| |
| jr +++ |
1.1x +jr+hash...........................................................####.........................................+-+
| +++#| # |
| | #++# |
1.08x +-+................................+++................+++.+++..*****..#.........................................+-+
| | +++ | | * | * # |
| | | | | *+++* # |
1.06x +-+................................****###.............|...|...*...*..#.........................+++.............+-+
| *| * |# ****### * * # | |
| *| *++# *| * |# * * # #### |
1.04x +-+................................*++*..#............*|.*.|#..*...*..#........................#.|#.............+-+
| * * # *++*++# * * # +++#++# |
| * * # * * # * * # | # # +++#### |
1.02x +-+................................*..*..#......+++...*..*..#..*...*..#.....................****..#..*****++#...+-+
| +++ * * # +++ | * * # * * # +++ *| * # *+++* # |
| +++ | +++ +++ ++++++ * * # *****### * * # * * # | +++ ++++++ *++* # * * # |
1x +-++-+++++####++****###++++-+####+-*++*++#-+*+++*-+#++*++*++#++*+-+*++#+-+++####-+*****###++*++*++#++*+-+*++#+-++-+
| *****| # *++* |# *****| # * * # * *++# * * # * * # **** |# * * # * * # * * # |
| * | *| # * *++# * | *++# * * # * * # * * # * * # *| *++# * * # * * # * * # |
0.98x +-+...*.|.*++#..*..*..#..*+++*..#..*..*..#..*...*..#..*..*..#..*...*..#..*++*..#..*...*..#..*..*..#..*...*..#...+-+
| *+++* # * * # * * # * * # * * # * * # * * # * * # * * # * * # * * # |
| * * # * * # * * # * * # * * # * * # * * # * * # * * # * * # * * # |
0.96x +-+---*****###--****###--*****###--****###--*****###--****###--*****###--****###--*****###--****###--*****###---+-+
ASSIGNMENT BITFIELD FOURFP EMULATION HUFFMAN LU DECOMPOSITIONEURAL NNUMERIC SOSTRING SORT hmean
png: http://imgur.com/ZXFX0hJ
- NBench, arm-linux-user. Host: Intel i7-4790K @ 4.00GHz
1.3x +-+-------------------------------------------------------------------------------------------------------------+-+
| #### |
| jr # # +++ |
1.25x +jr+hash.....................#..#...........................................####................................+-+
| # # # # |
| # # # # |
1.2x +-+..........................#..#...........................................#..#................................+-+
| # # # # |
| # # # # |
1.15x +-+..........................#..#...........................................#..#................................+-+
| # # #### # # |
| # # # # # # |
1.1x +-+..........................#..#..................................#..#.....#..#................................+-+
| # # # # # # +++ |
| # # #### # # # # #### |
1.05x +-+..........................#..#...............#..#.....####......#..#.....#..#.........................#..#...+-+
| # # # # # # # # # # +++ # # |
| +++ ***** # #### ***** # # # +++# # **** # ****### # # |
1x +-++-+*****###++****+++++*+-+*++#+-****++#-+*+++*-+#+++++#++#++*****++#+-*++*++#-+*****-++++*++*++#++*****++#+-++-+
| * * # * * | * * # * * # * * # **** # * * # * * # * *### * *++# * * # |
| * * # * *### * * # * * # * * # * * # * * # * * # * * # * * # * * # |
0.95x +-+...*...*..#..*..*.|#..*...*..#..*..*..#..*...*..#..*..*..#..*...*..#..*..*..#..*...*..#..*..*..#..*...*..#...+-+
| * * # * * |# * * # * * # * * # * * # * * # * * # * * # * * # * * # |
| * * # * * |# * * # * * # * * # * * # * * # * * # * * # * * # * * # |
0.9x +-+---*****###--****###--*****###--****###--*****###--****###--*****###--****###--*****###--****###--*****###---+-+
ASSIGNMENT BITFIELD FOURFP EMULATION HUFFMAN LU DECOMPOSITIONEURAL NNUMERIC SOSTRING SORT hmean
png: http://imgur.com/FfD27ey
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Richard Henderson <rth@twiddle.net>
Signed-off-by: Emilio G. Cota <cota@braap.org>
Message-Id: <1493263764-18657-12-git-send-email-cota@braap.org>
Signed-off-by: Richard Henderson <rth@twiddle.net>
---
include/exec/tb-hash.h | 12 ++++++++++++
1 file changed, 12 insertions(+)
diff --git a/include/exec/tb-hash.h b/include/exec/tb-hash.h
index 2c27490..b1fe2d0 100644
--- a/include/exec/tb-hash.h
+++ b/include/exec/tb-hash.h
@@ -22,6 +22,8 @@
#include "exec/tb-hash-xx.h"
+#ifdef CONFIG_SOFTMMU
+
/* Only the bottom TB_JMP_PAGE_BITS of the jump cache hash bits vary for
addresses on the same page. The top bits are the same. This allows
TLB invalidation to quickly clear a subset of the hash table. */
@@ -45,6 +47,16 @@ static inline unsigned int tb_jmp_cache_hash_func(target_ulong pc)
| (tmp & TB_JMP_ADDR_MASK));
}
+#else
+
+/* In user-mode we can get better hashing because we do not have a TLB */
+static inline unsigned int tb_jmp_cache_hash_func(target_ulong pc)
+{
+ return (pc ^ (pc >> TB_JMP_CACHE_BITS)) & (TB_JMP_CACHE_SIZE - 1);
+}
+
+#endif /* CONFIG_SOFTMMU */
+
static inline
uint32_t tb_hash_func(tb_page_addr_t phys_pc, target_ulong pc, uint32_t flags)
{
--
2.9.4
next prev parent reply other threads:[~2017-06-05 16:52 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-06-05 16:52 [Qemu-devel] [PULL 00/26] tcg queued patches Richard Henderson
2017-06-05 16:52 ` [Qemu-devel] [PULL 01/26] target/nios2: Fix 64-bit ilp32 compilation Richard Henderson
2017-06-05 16:52 ` [Qemu-devel] [PULL 02/26] tcg/sparc: Use the proper compilation flags for 32-bit Richard Henderson
2017-06-05 16:52 ` [Qemu-devel] [PULL 03/26] qemu/atomic: Loosen restrictions for 64-bit ILP32 hosts Richard Henderson
2017-06-05 16:52 ` [Qemu-devel] [PULL 04/26] tcg: Introduce goto_ptr opcode and tcg_gen_lookup_and_goto_ptr Richard Henderson
2017-06-05 16:52 ` [Qemu-devel] [PULL 05/26] tcg/i386: implement goto_ptr Richard Henderson
2017-06-05 16:52 ` [Qemu-devel] [PULL 06/26] target/arm: optimize cross-page direct jumps in softmmu Richard Henderson
2017-06-05 16:52 ` [Qemu-devel] [PULL 07/26] target/arm: optimize indirect branches Richard Henderson
2017-06-05 16:52 ` [Qemu-devel] [PULL 08/26] target/i386: introduce gen_jr helper to generate lookup_and_goto_ptr Richard Henderson
2017-06-05 16:52 ` [Qemu-devel] [PULL 09/26] target/i386: optimize cross-page direct jumps in softmmu Richard Henderson
2017-06-05 16:52 ` [Qemu-devel] [PULL 10/26] target/i386: optimize indirect branches Richard Henderson
2017-06-05 16:52 ` Richard Henderson [this message]
2017-06-05 16:52 ` [Qemu-devel] [PULL 12/26] tcg/ppc: Implement goto_ptr Richard Henderson
2017-06-05 16:52 ` [Qemu-devel] [PULL 13/26] tcg/aarch64: " Richard Henderson
2017-06-05 16:52 ` [Qemu-devel] [PULL 14/26] tcg/sparc: " Richard Henderson
2017-06-05 16:52 ` [Qemu-devel] [PULL 15/26] tcg/s390: " Richard Henderson
2017-06-05 16:52 ` [Qemu-devel] [PULL 16/26] tcg/arm: Clarify tcg_out_bx for arm4 host Richard Henderson
2017-06-05 16:52 ` [Qemu-devel] [PULL 17/26] tcg/arm: Implement goto_ptr Richard Henderson
2017-06-05 16:52 ` [Qemu-devel] [PULL 19/26] target/s390: Use tcg_gen_lookup_and_goto_ptr Richard Henderson
2017-06-05 16:52 ` [Qemu-devel] [PULL 20/26] target/hppa: " Richard Henderson
2017-06-05 16:52 ` [Qemu-devel] [PULL 21/26] target/aarch64: optimize cross-page direct jumps in softmmu Richard Henderson
2017-06-05 16:52 ` [Qemu-devel] [PULL 22/26] target/aarch64: optimize indirect branches Richard Henderson
2017-06-07 14:11 ` Alex Bennée
2017-06-07 14:22 ` Alex Bennée
2017-06-07 15:19 ` Alex Bennée
2017-06-07 15:52 ` Alex Bennée
2017-06-07 20:22 ` Emilio G. Cota
2017-06-08 10:48 ` Alex Bennée
2017-06-07 20:38 ` Richard Henderson
2017-06-08 8:38 ` Alex Bennée
2017-06-05 16:52 ` [Qemu-devel] [PULL 23/26] target/mips: optimize cross-page direct jumps in softmmu Richard Henderson
2017-06-05 16:52 ` [Qemu-devel] [PULL 24/26] target/mips: optimize indirect branches Richard Henderson
2017-06-05 16:52 ` [Qemu-devel] [PULL 25/26] target/alpha: Implement WTINT inline Richard Henderson
2017-06-05 16:52 ` [Qemu-devel] [PULL 26/26] target/alpha: Use goto_tb for fallthru between TBs Richard Henderson
2017-06-06 8:56 ` [Qemu-devel] [PULL 00/26] tcg queued patches Peter Maydell
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