[PATCH v15 10/10] docs: add tb-stats how to

[Fei Wu]

Signed-off-by: Fei Wu <fei2.wu@intel.com>
---
 docs/devel/tcg-tbstats.rst | 97 ++++++++++++++++++++++++++++++++++++++
 1 file changed, 97 insertions(+)
 create mode 100644 docs/devel/tcg-tbstats.rst

diff --git a/docs/devel/tcg-tbstats.rst b/docs/devel/tcg-tbstats.rst
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+============
+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 [flag] -- Control tb statistics collection:tb_stats 
(start|stop|status) [all|jit|exec]
+
+    (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:0 | 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
+
+    TB id:1 | 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
+
+* Dive into the specific TB::
+
+    (qemu) info tb 1
+    ------------------------------
+
+    TB id:0 | 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
+
+    ------------------------------
+
+* Stop TBStatistics after investigation, this will disable TBStatistics 
completely.::
+
+    (qemu) tb_stats stop
+    (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_{all,jit,exec}[:dump_num_at_exit]
+
+e.g. starting qemu like this:::
+
+    -d tb_stats_all: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
+
+    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
-- 
2.25.1