linux-kernel - modifying CFS failure

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Message-ID: <42423.210.212.49.15.1207972006.squirrel@mail.mnnit.ac.in>
Date:	Sat, 12 Apr 2008 09:16:46 +0530 (IST)
From:	cs044024@...it.ac.in
To:	linux-kernel@...r.kernel.org
Subject: modifying CFS failure

We tried to replace RB-Trees in CFS by AVL trees to compare the
performance benchmarks. For this we wrote a code for avl tree, and made
changes in sched-cfs-v2.6.22.13-v24.patch by replacing each occurance of
RB-tree function by corrosponding AVL tree function. We successfully
applied the patch on the required kernel version and successfully compiled
it. But we are not able to boot the kernel. Following are important
portions from the boot error

call trace

enqueue_entity
enqueue_task_fair
enqueue_task
activate_task
wake_up_new_task
do_fork
kernel_init
kernel_thread
kernel_init
kernel_thread_helper
rest_init
start_kernel
unknown_boot option

EIP[<c01e3a76>] insert_avl_node kernel panic attempting to kill the idle
task!

insert_avl_node is the function to insert a node in the avl tree.

We have properly tested the avl tree code and its working fine. After
trying to trace the error for a few days, we feel that we may be missing
something (In addition to replacing all the occurances of RB by avl in the
patch and including the avl tree code in kernel library)

Attached with this mail are the avl tree codes, the modified patch. The
patch is same as the file sched-cfs-v2.6.22.13-v24.patch, except all the
occurances of RB tree have been replaced by corrosponding functions of avl
tree.

At present we are devoid of any ideas of proceeding forward with the task.
We shall be thankful if someone can guide us to proceed further and
rectifying the errors.

Rohit Gupta
NIT Allahabad India

View attachment "avltree-v1.c" of type "text/x-csrc" (12004 bytes)

View attachment "avltree-v1.h" of type "text/x-chdr" (1268 bytes)

View attachment "sched-cfs-v2.6.22.13-v24-v1.patch" of type "text/x-patch" (379915 bytes)