Signed-off-by: Fei Wu <fei2...@intel.com> --- docs/devel/tcg-tbstats.rst | 129 +++++++++++++++++++++++++++++++++++++ 1 file changed, 129 insertions(+) create mode 100644 docs/devel/tcg-tbstats.rst
diff --git a/docs/devel/tcg-tbstats.rst b/docs/devel/tcg-tbstats.rst new file mode 100644 index 0000000000..bfba222e96 --- /dev/null +++ b/docs/devel/tcg-tbstats.rst @@ -0,0 +1,129 @@ +============ +TBStatistics +============ + +What is TBStatistics +==================== + +TBStatistics (tb_stats) is a tool to gather various internal information of TCG +during binary translation, this allows us to identify such as hottest TBs, +guest to host instruction translation ratio, number of spills during register +allocation and more. + + +How to use TBStatistics +======================= + +1. HMP interface +---------------- + +TBStatistics provides HMP interface, you can try the following examples after +connecting to the monitor. + +* First check the help info:: + + (qemu) help tb_stats + tb_stats command [stats_level] -- Control tb statistics collection:tb_stats (start|pause|stop|filter) [all|jit_stats|exec_stats] + + (qemu) help info tb-list + info tb-list [number sortedby] -- show a [number] translated blocks sorted by [sortedby]sortedby opts: hotness hg spills + + (qemu) help info tb + info tb id [flag1,flag2,...] -- show information about one translated block by id.dump flags can be used to set dump code level: out_asm in_asm op + +* Enable TBStatistics:: + + (qemu) tb_stats start all + (qemu) + +* Get interested TB list:: + + (qemu) info tb-list 2 + TB id:1 | phys:0x79bca0 virt:0xffffffff8059bca0 flags:0x01024001 0 inv/1 + | exec:1464084/0 guest inst cov:0.15% + | trans:1 ints: g:3 op:16 op_opt:15 spills:0 + | h/g (host bytes / guest insts): 64.000000 + | time to gen at 2.4GHz => code:607.08(ns) IR:250.83(ns) + + TB id:2 | phys:0x2adf0c virt:0xffffffff800adf0c flags:0x01024001 0 inv/1 + | exec:1033298/0 guest inst cov:0.28% + | trans:1 ints: g:8 op:35 op_opt:33 spills:0 + | h/g (host bytes / guest insts): 86.000000 + | time to gen at 2.4GHz => code:1429.58(ns) IR:545.42(ns) + +* Dive into the specific TB:: + + (qemu) info tb 1 op + ------------------------------ + + TB id:1 | phys:0x79bca0 virt:0xffffffff8059bca0 flags:0x01024001 7 inv/19 + | exec:2038349/0 guest inst cov:0.15% + | trans:19 ints: g:3 op:16 op_opt:15 spills:0 + | h/g (host bytes / guest insts): 64.000000 + | time to gen at 2.4GHz => code:133434.17(ns) IR:176988.33(ns) + + OP: + ld_i32 loc1,env,$0xfffffffffffffff0 + brcond_i32 loc1,$0x0,lt,$L0 + mov_i64 loc3,$0x7f3c70b3a4e0 + call inc_exec_freq,$0x1,$0,loc3 + + ---- ffffffff8059bca0 0000000000006422 + add_i64 loc5,x2/sp,$0x8 + qemu_ld_i64 x8/s0,loc5,un+leq,1 + + ---- ffffffff8059bca2 0000000000000000 + add_i64 x2/sp,x2/sp,$0x10 + + ---- ffffffff8059bca4 0000000000000000 + mov_i64 pc,x1/ra + and_i64 pc,pc,$0xfffffffffffffffe + call lookup_tb_ptr,$0x6,$1,tmp9,env + goto_ptr tmp9 + set_label $L0 + exit_tb $0x7f3e887a8043 + + ------------------------------ + +* Stop TBStatistics after investigation, this will disable TBStatistics completely.:: + + (qemu) tb_stats stop + (qemu) + +* Alternatively, TBStatistics can be paused, the previous collected TBStatistics + are not cleared but there is no TBStatistics recorded for new TBs.:: + + (qemu) tb_stats pause + (qemu) + +* Definitely, TBStatistics can be restarted for another round of investigation.:: + + (qemu) tb_stats start all + (qemu) + + +2. Dump at exit +--------------- + +New command line options have been added to enable dump TB information at exit::: + + -d tb_stats[[,level=(+all+jit+exec+time)][,dump_limit=<number>]] + +e.g. starting qemu like this::: + + -d tb_stats,dump_limit=2 + +Qemu prints the following at exit::: + + QEMU: Terminated + TB id:1 | phys:0x61be02 virt:0xffffffff8041be02 flags:0x01024001 0 inv/1 + | exec:72739176/0 guest inst cov:20.22% + | trans:1 ints: g:9 op:35 op_opt:33 spills:0 + | h/g (host bytes / guest insts): 51.555557 + | time to gen at 2.4GHz => code:1065.42(ns) IR:554.17(ns) + + TB id:2 | phys:0x61bc66 virt:0xffffffff8041bc66 flags:0x01024001 0 inv/1 + | exec:25069507/0 guest inst cov:0.77% + | trans:1 ints: g:1 op:15 op_opt:14 spills:0 + | h/g (host bytes / guest insts): 128.000000 + | time to gen at 2.4GHz => code:312.50(ns) IR:152.08(ns) -- 2.25.1
