Adding ioblame. A tool for App IO profiling.

ioblame is a tool for profiling App IO workloads. See the README for
more details on ioblame and how to use it.

Change-Id: Id56f827c2a8b744e24e3b21b535a59bd458f3de4
Signed-off-by: Mohan Srinivasan <[email protected]>

ioblame/Android.mk

@@ -0,0 +1,5 @@
+LOCAL_PATH:= $(call my-dir)
+
+include $(CLEAR_VARS)
+LOCAL_PREBUILT_EXECUTABLES := ioblame.sh
+include $(BUILD_HOST_PREBUILT)

ioblame/README

@@ -0,0 +1,200 @@
+What is it ?
+----------
+ioblame is a IO profiler. It gives a detailed listing of the list of
+files that running pids are doing IO to (with the aggregate amount of
+read/write to each file). The goal is that using this tool, app
+developers can identify IO heavy paths, and tune them, then
+iteratively run this tool again to measure improvements/IO reduction.
+
+ioblame is implemented as a collection of kernel filesystem
+tracepoints, and a script.
+
+What does the output from ioblame look like ?
+-------------------------------------------
+ioblame gives 2 different views.
+
+1) File view : For each file, it gives a list of pids that are doing
+IO on that file (it also gives the amount of IO each pid does and
+the aggregate amount of IO done to the file by all pids).
+
+File: /app/Chrome/Chrome.apk
+            Chrome_ChildIOT Reads: 96 KB
+            Chrome_DBThread Reads: 652 KB
+            Chrome_FileUser Reads: 72 KB
+            Chrome_InProcGp Reads: 732 KB
+            Chrome_IOThread Reads: 1396 KB
+            Compositor Reads: 652 KB
+            CookieMonsterBa Reads: 284 KB
+            CrRendererMain Reads: 17012 KB
+            dboxed_process0 Reads: 512 KB
+            JavaBridge Reads: 128 KB
+            ogle.android.gm Reads: 14996 KB
+            WorkerPool/8556 Reads: 408 KB
+            Total Reads: 36940 KB i_size: 71354 KB
+File: /app/Gmail2Light/Gmail2Light.apk
+            AsyncTask_#2 Reads: 24 KB
+            Chrome_IOThread Reads: 68 KB
+            ogle.android.gm Reads: 1440 KB
+            Thread-6 Reads: 8 KB
+            Total Reads: 1540 KB i_size: 9736 KB
+
+And ditto for writes.
+
+2) PID view : For each pid actively doing IO, it dumps out the list of
+files that the pid does IO to.
+
+PID: CrRendererMain
+            /app/Chrome/Chrome.apk Reads: 17012 KB i_size: 71354 KB
+            /etc/fonts.xml Reads: 24 KB i_size: 22 KB
+            /fonts/CarroisGothicSC-Regular.ttf Reads: 40 KB i_size: 39 KB
+            /fonts/ComingSoon.ttf Reads: 60 KB i_size: 57 KB
+            /fonts/CutiveMono.ttf Reads: 68 KB i_size: 67 KB
+            /fonts/DancingScript-Bold.ttf Reads: 116 KB i_size: 112 KB
+            /fonts/DancingScript-Regular.ttf Reads: 116 KB i_size: 113 KB
+            /fonts/DroidSansMono.ttf Reads: 108 KB i_size: 105 KB
+            /fonts/NotoColorEmoji.ttf Reads: 204 KB i_size: 7108 KB
+            /fonts/NotoNaskhArabic-Bold.ttf Reads: 116 KB i_size: 113 KB
+,,,
+	    /fonts/NotoSerif-BoldItalic.ttf Reads: 248 KB i_size: 256 KB
+            /fonts/NotoSerif-Bold.ttf Reads: 244 KB i_size: 242 KB
+            /fonts/NotoSerif-Italic.ttf Reads: 244 KB i_size: 243 KB
+            /fonts/NotoSerif-Regular.ttf Reads: 244 KB i_size: 240 KB
+            /fonts/Roboto-BlackItalic.ttf Reads: 256 KB i_size: 322 KB
+            /fonts/Roboto-Black.ttf Reads: 256 KB i_size: 299 KB
+            /fonts/Roboto-BoldItalic.ttf Reads: 256 KB i_size: 324 KB
+            /fonts/RobotoCondensed-BoldItalic.ttf Reads: 256 KB i_size: 322 KB
+            /fonts/RobotoCondensed-Bold.ttf Reads: 256 KB i_size: 296 KB
+            /fonts/RobotoCondensed-Italic.ttf Reads: 256 KB i_size: 321 KB
+            /fonts/RobotoCondensed-LightItalic.ttf Reads: 256 KB i_size: 324 KB
+            /fonts/RobotoCondensed-Light.ttf Reads: 256 KB i_size: 295 KB
+            /fonts/RobotoCondensed-MediumItalic.ttf Reads: 256 KB i_size: 322 KB
+            /fonts/RobotoCondensed-Medium.ttf Reads: 256 KB i_size: 296 KB
+            /fonts/Roboto-LightItalic.ttf Reads: 256 KB i_size: 324 KB
+            /fonts/Roboto-MediumItalic.ttf Reads: 256 KB i_size: 323 KB
+            /fonts/Roboto-Regular.ttf Reads: 88 KB i_size: 298 KB
+            /fonts/Roboto-ThinItalic.ttf Reads: 256 KB i_size: 321 KB
+            /fonts/Roboto-Thin.ttf Reads: 256 KB i_size: 300 KB
+            /lib/libft2.so Reads: 56 KB i_size: 479 KB
+            /lib/libicuuc.so Reads: 88 KB i_size: 1182 KB
+            Total Reads: 32760 KB
+
+And ditto for writes.
+
+Finally, it reports the total amount of file data IO done by pids and
+the total IO done to the block device. So we can look at IO overheads
+(eg block level prefetching, filesystem metadata overhead etc).
+
+For detailed examples, look at ioblame-gmail-launch.example and
+ioblame-gmail-run.example.
+
+How do I run ioblame ?
+--------------------
+ioblame -r	[ I am only interested in reads ]
+ioblame -w	[ I am only interested in writes ]
+ioblame -r -w  [ I am only interested in reads and writes ]
+
+1) The most common way of running ioblame is to start ioblame, then go
+off and launch the app(s) of interest, do interesting stuff with the
+app(s), and when finished with the app, hit ^C ONCE on
+ioblame. Hitting ^C once will cause ioblame to catch the signal, break
+out of the sleep, terminate its tracing, and process the ftraces and
+dump out IO stats for the app.
+
+example :
+
+srmohan0.mtv.corp.google.com> sh ioblame.sh  -r -w
+Found aosp_gobo Device
+OK to kill sleep when test is done
+^Csignal INT received, killing streaming trace capture
+
+(at this point, run your apps, when done type ^C ONCE) and output will
+appear on stdout.
+
+2) Sometimes, we want to do IO profiling in a different way (instead of
+running something and then hitting ^C on ioblame). For instance, we
+might want to do IO profiling related to the launch of an App. This
+requires you to modify the script slightly, as described in the next
+paragraph.
+
+If you want to do IO profiling related to App launch, you need to modify
+2 functions - prep_to_do_something and do_something. Again examples of
+changes to these functions clarifies things better :
+
+prep_to_do_something() {
+    adb shell "am force-stop com.google.android.gm" # This line I added for example
+    	      	  	     			    # stops the running app (gmail)
+    adb shell 'echo 3 > /proc/sys/vm/drop_caches'
+    sleep 1
+}
+
+do_something() {
+    # Arrange things so that the first SIGINT will kill the
+    # child process (sleep), but will return to the parent.
+#    trap 'catch_sigint'  INT
+#    echo "OK to kill sleep when test is done"
+#    sleep 1d
+     # For the purpose of this example, I commented out the above 3 lines that
+     # make ioblame sleep forever after catching the SIGINT and instead it launches
+     # gmail, waiting for launch to complete. When launch completes, ioblame will
+     # stop tracing, and process the traces
+    adb shell "am start -W -n com.google.android.gm/.ConversationListActivityGmail"
+}
+
+Limitations :
+-----------
+The ioblame kernel tracepoints currently only cover the getpage(s)
+path (so all filesystem reads) and filesystem write() syscalls. There
+are no tracepoints in the putpage(s) paths. This is because when
+putpage(s) is called, we most often cannot tell which thread/pid has
+dirtied the page that is being written out, because the majority of
+putpage(s) happen from the flush threads or from the pageout
+threads. The upshot of this is the mmap'ed writes are not reported by
+ioblame. In practice, while mmap'ed reads are very common, mmap'ed
+writes are infrequent.
+
+Kernel Patches Required :
+-----------------------
+ioblame needs the kernel to be patched with these 3 kernel patches.
+Without these patches, ioblame won't work at all.
+
+commit ae2f6765db98e2fcb99082e336dd8b24e7644620
+Author: Mohan Srinivasan <[email protected]>
+Date:   Fri Mar 10 16:08:30 2017 -0800
+
+    ANDROID: Replace spaces by '_' for some android filesystem tracepoints.
+
+    Andoid files frequently have spaces in them, as do cmdline strings.
+    Replace these spaces with '_', so tools that parse these tracepoints
+    don't get terribly confused.
+
+    Change-Id: I1cbbedf5c803aa6a58d9b8b7836e9125683c49d1
+    Signed-off-by: Mohan Srinivasan <[email protected]>
+    (cherry picked from commit 5035d5f0933758dd515327d038e5bef7e40dbaa7)
+
+commit a2a04ea83d2960867324fa059ba1eedc2fc7784e (HEAD -> android-4.4)
+Author: Mohan Srinivasan <[email protected]>
+Date:   Fri Feb 3 15:48:03 2017 -0800
+
+    ANDROID: Refactor fs readpage/write tracepoints.
+
+    Refactor the fs readpage/write tracepoints to move the
+    inode->path lookup outside the tracepoint code, and pass a pointer
+    to the path into the tracepoint code instead. This is necessary
+    because the tracepoint code runs non-preemptible. Thanks to
+    Trilok Soni for catching this in 4.4.
+
+    Change-Id: I7486c5947918d155a30c61d6b9cd5027cf8fbe15
+    Signed-off-by: Mohan Srinivasan <[email protected]>
+
+commit 32cbbe59538d2dd0b77822cc27ce32ca487c467d
+Author: Mohan Srinivasan <[email protected]>
+Date:   Mon Sep 19 17:33:50 2016 -0700
+
+    ANDROID: fs: FS tracepoints to track IO.
+
+    Adds tracepoints in ext4/f2fs/mpage to track readpages/buffered
+    write()s. This allows us to track files that are being read/written
+    to PIDs.
+
+    Change-Id: I26bd36f933108927d6903da04d8cb42fd9c3ef3d
+    Signed-off-by: Mohan Srinivasan <[email protected]>