On Thu, Dec 4, 2014 at 2:55 PM, Brendan Gregg <brendan.d.gr...@gmail.com
<mailto:brendan.d.gr...@gmail.com>> wrote:
G'Day,
I've hacked hotspot to return the frame pointer, in part to see what
this involves, and also to have a working prototype for analysis.
Along with an agent to resolve symbols, this has allowed full stack
profiling using Linux perf_events. The following flame graphs show
the resulting profiles.
A mixed mode CPU flame graph of a vert.x benchmark (click to zoom):
http://www.brendangregg.com/FlameGraphs/cpu-mixedmode-vertx.svg
Same thing, but this time disabling inlining, to show more frames:
http://www.brendangregg.com/FlameGraphs/cpu-mixedmode-flamegraph.svg
As expected, performance is worse without inlining. You can compare
the flame graphs side by side to see why. Less time spent doing work
/ I/O!
https://github.com/brendangregg/Misc/blob/master/java/openjdk8_b132-fp.diff
is my patch,
[...]
In case there's problems with the patch URL, the patch is:
--- openjdk8clean/hotspot/src/cpu/x86/vm/x86_64.ad <http://x86_64.ad>
2014-03-04 02:52:11.000000000 +0000
+++ openjdk8/hotspot/src/cpu/x86/vm/x86_64.ad <http://x86_64.ad>
2014-11-08 01:10:49.686044933 +0000
@@ -166,10 +166,9 @@
// 3) reg_class stack_slots( /* one chunk of stack-based "registers" */ )
//
-// Class for all pointer registers (including RSP)
+// Class for all pointer registers (including RSP, excluding RBP)
reg_class any_reg(RAX, RAX_H,
RDX, RDX_H,
- RBP, RBP_H,
RDI, RDI_H,
RSI, RSI_H,
RCX, RCX_H,
@@ -184,10 +183,9 @@
R14, R14_H,
R15, R15_H);
-// Class for all pointer registers except RSP
+// Class for all pointer registers except RSP and RBP
reg_class ptr_reg(RAX, RAX_H,
RDX, RDX_H,
- RBP, RBP_H,
RDI, RDI_H,
RSI, RSI_H,
RCX, RCX_H,
@@ -199,9 +197,8 @@
R13, R13_H,
R14, R14_H);
-// Class for all pointer registers except RAX and RSP
+// Class for all pointer registers except RAX, RSP and RBP
reg_class ptr_no_rax_reg(RDX, RDX_H,
- RBP, RBP_H,
RDI, RDI_H,
RSI, RSI_H,
RCX, RCX_H,
@@ -226,9 +223,8 @@
R13, R13_H,
R14, R14_H);
-// Class for all pointer registers except RAX, RBX and RSP
+// Class for all pointer registers except RAX, RBX, RSP and RBP
reg_class ptr_no_rax_rbx_reg(RDX, RDX_H,
- RBP, RBP_H,
RDI, RDI_H,
RSI, RSI_H,
RCX, RCX_H,
@@ -260,10 +256,9 @@
// Singleton class for TLS pointer
reg_class ptr_r15_reg(R15, R15_H);
-// Class for all long registers (except RSP)
+// Class for all long registers (except RSP and RBP)
reg_class long_reg(RAX, RAX_H,
RDX, RDX_H,
- RBP, RBP_H,
RDI, RDI_H,
RSI, RSI_H,
RCX, RCX_H,
@@ -275,9 +270,8 @@
R13, R13_H,
R14, R14_H);
-// Class for all long registers except RAX, RDX (and RSP)
-reg_class long_no_rax_rdx_reg(RBP, RBP_H,
- RDI, RDI_H,
+// Class for all long registers except RAX, RDX (and RSP, RBP)
+reg_class long_no_rax_rdx_reg(RDI, RDI_H,
RSI, RSI_H,
RCX, RCX_H,
RBX, RBX_H,
@@ -288,9 +282,8 @@
R13, R13_H,
R14, R14_H);
-// Class for all long registers except RCX (and RSP)
-reg_class long_no_rcx_reg(RBP, RBP_H,
- RDI, RDI_H,
+// Class for all long registers except RCX (and RSP, RBP)
+reg_class long_no_rcx_reg(RDI, RDI_H,
RSI, RSI_H,
RAX, RAX_H,
RDX, RDX_H,
@@ -302,9 +295,8 @@
R13, R13_H,
R14, R14_H);
-// Class for all long registers except RAX (and RSP)
-reg_class long_no_rax_reg(RBP, RBP_H,
- RDX, RDX_H,
+// Class for all long registers except RAX (and RSP, RBP)
+reg_class long_no_rax_reg(RDX, RDX_H,
RDI, RDI_H,
RSI, RSI_H,
RCX, RCX_H,
@@ -325,10 +317,9 @@
// Singleton class for RDX long register
reg_class long_rdx_reg(RDX, RDX_H);
-// Class for all int registers (except RSP)
+// Class for all int registers (except RSP and RBP)
reg_class int_reg(RAX,
RDX,
- RBP,
RDI,
RSI,
RCX,
@@ -340,10 +331,9 @@
R13,
R14);
-// Class for all int registers except RCX (and RSP)
+// Class for all int registers except RCX (and RSP, RBP)
reg_class int_no_rcx_reg(RAX,
RDX,
- RBP,
RDI,
RSI,
RBX,
@@ -355,8 +345,7 @@
R14);
// Class for all int registers except RAX, RDX (and RSP)
-reg_class int_no_rax_rdx_reg(RBP,
- RDI,
+reg_class int_no_rax_rdx_reg(RDI,
RSI,
RCX,
RBX,
@@ -718,6 +707,7 @@
st->print("# stack bang");
st->print("\n\t");
st->print("pushq rbp\t# Save rbp");
+ // BDG consider: st->print("movq rbp, rsp\t# ");
if (framesize) {
st->print("\n\t");
st->print("subq rsp, #%d\t# Create frame",framesize);
--- openjdk8clean/hotspot/src/cpu/x86/vm/macroAssembler_x86.cpp
2014-03-04 02:52:11.000000000 +0000
+++ openjdk8/hotspot/src/cpu/x86/vm/macroAssembler_x86.cpp 2014-11-07
23:57:11.589593723 +0000
@@ -5236,6 +5236,7 @@
// We always push rbp, so that on return to interpreter rbp, will be
// restored correctly and we can correct the stack.
push(rbp);
+ mov(rbp, rsp);
// Remove word for ebp
framesize -= wordSize;
--- openjdk8clean/hotspot/src/cpu/x86/vm/c1_MacroAssembler_x86.cpp
2014-03-04 02:52:10.000000000 +0000
+++ openjdk8/hotspot/src/cpu/x86/vm/c1_MacroAssembler_x86.cpp
2014-11-07 23:57:21.933257882 +0000
@@ -358,6 +358,7 @@
generate_stack_overflow_check(frame_size_in_bytes);
push(rbp);
+ mov(rbp, rsp);
#ifdef TIERED
// c2 leaves fpu stack dirty. Clean it on entry
if (UseSSE < 2 ) {
Brendan
