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[Qemu-devel] Trying to Understand QEMU's Low Level Functionality ...


From: Atoosaah S
Subject: [Qemu-devel] Trying to Understand QEMU's Low Level Functionality ...
Date: Tue, 23 Oct 2007 16:33:05 -0700

I'm using qemu version 0.8.2 on linux.

I'm currently successful in creating the result.txt (with the command: prof /intsall_path/qemu gmon.out > result.txt), but the call graph created does not show my functions of interest.

For example i'm trying to understand the sequence of calls qemu makes to read/write from the disk image. Using print statements i see the function ide_read_dma_cb (from hw directory, file ide.c) being called; as well as bdrv_read from (qemu root directory, file block.c). The only ide function i see in result.txt is ide_init2 and ide_init_ioport, and the only bdrv type functions are bdrv_open2 and bdrv_new. But, listing the symbol table via "nm" on qemu, does display my functions of interest ( i.e. bdrv_read, bdrv_write, ...). I should see these functions in the gprof result since, for example, they are executed frequently (during OS bootup, and writting/reading to/from a sample large file)

1. Why am I only seeing specific low level functions in the call graph?
2. Is there a more clear way of finding out how (i.e. sequence of calls) qemu make to write to the disk image?

thank you,
atoosaah




On 10/12/07, Atoosaah wrote:
I'd appreciate any input on how to run gprof successfully on qemu. I'm new to gprof and am probably missing some steps.  I successfully ran gprof on a sorting program available online, then I attempted to run gprof on qemu.

Here are the steps I take:

I'm trying to run gprof on qemu, but am unsuccessful. my os is linux, my qemu version is 0.8.2. I configure qemu with the options "configure --prefix=/install_path --enable-gprof. Then I make and make install. I run qemu successfully using the options /install_path/qemu -hda diskimage.img -m 256 which results in the gmon.out file. My run of qemu involved starting the image (virtual linux OS), running a few simple commands and shutting the image down.

Finally, I run gprof /intsall_path/qemu gmon.out > result.txt which gives the error: gprof: file 'qemu' has no symbols'

Are there any other configuration options required? Should the image be run with differently?


thank you,
atoosaah


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