http://www.xbwolf.com/507
http://blog.csdn.net/kafeiflynn/article/details/6429976
安裝步驟yum install systemtap
/usr/share/doc/systemtap-client-2.7/examples/
要遵循stap的寫法,要求2.6.11內核以上的機器使用。
初次訪問報錯:
emantic error: while resolving probe point: identifier ‘kernel’ at /usr/share/systemtap/tapset/linux/vfs.stp:918:19
source: probe vfs.write = kernel.function(“vfs_write”)
semantic error: missing x86_64 kernel/module debuginfo [man warning::debuginfo] under ‘/lib/modules/2.6.32-431.23.3.el6.x86_64/build’
semantic error: while resolving probe point: identifier ‘vfs’ at inodewatch.stp:3:7
source: probe vfs.write, vfs.read
semantic error: no match
測試機器是: centos6
yum裝的有kernel-devel kernel-headers gcc elfutils
通過 http://debuginfo.centos.org/6/x86_64/ 下載kernel-debug-debuginfo 以及kernel-debuginfo-common
主要要下載對應內核版本的,例如測試機器下載
kernel-debug-debuginfo-2.6.32-431.23.3.el6.x86_64.rpm 260M左右
kernel-debuginfo-common-x86_64-2.6.32-431.23.3.el6.x86_64.rpm 40m左右
rpm安裝好后執行
WARNING: cannot find module nfs debuginfo: No DWARF information found [man warning::debuginfo]
WARNING: cannot find module sunrpc debuginfo: No DWARF information found [man warning::debuginfo]
說明包沒下載對
stap-prep 命令查看到
Need to install the following packages:
kernel-debuginfo-2.6.32-431.23.3.el6.x86_64
發現與之前找到的包不一致。這點要仔細。。。。
通過:stap -v -e ‘probe vfs.read {printf(“read performed\n”); exit()}’ 測試是否執行成功,從pass1最后到pass5
前面是安裝,下面開始說怎么用:
在/usr/share/doc/systemtap-client-2.7/examples/目錄下,有很多腳本
(通過褚霸大神的命令)
stap -e ‘probe vfs.add_to_page_cache {printf(“dev=%d, devname=%s, ino=%d, index=%d, nrpages=%d\n”, dev, devname, ino, index, nrpages )}’
看到此時段應用很小
上一篇文章我們創建了test.data,此刻這個文件5G大小,我們通過另一個終端CP一個,可以看到有大量的設備寫入
如:
dev=211812353, devname=xvda1, ino=1058100, index=2, nrpages=2
dev=211812353, devname=xvda1, ino=1058100, index=3, nrpages=3
dev=211812353, devname=xvda1, ino=1058100, index=4, nrpages=4
dev=211812353, devname=xvda1, ino=1058100, index=5, nrpages=5
dev=211812353, devname=xvda1, ino=1058100, index=6, nrpages=6
dev=211812353, devname=xvda1, ino=1058100, index=7, nrpages=7
dev=211812353, devname=xvda1, ino=1058100, index=8, nrpages=8
dev=211812353, devname=xvda1, ino=1058100, index=9, nrpages=9
dev=211812353, devname=xvda1, ino=1058100, index=10, nrpages=10
dev=211812353, devname=xvda1, ino=1058100, index=11, nrpages=11
同樣一個文件被頻繁寫入,被誰寫入如何查
ls -al /dev/xvda1
brw-rw—- 1 root disk 202, 1 Oct 27 09:07 /dev/xvda1
cp 一個文件。通過stat -c “%i” 文件查到inode
stap inodewatch.stg 202 1 ****
cp(2514) vfs_read 0xca00001/138740
cp(2514) vfs_read 0xca00001/138740
cp(2514) vfs_read 0xca00001/138740
查到是cp進程引起