March 2014 - kernelnewbies@kernelnewbies.org - Kernelnewbies Mailing Lists

thread context switching
by Nada Saif March 19, 2014

March 19, 2014

Hi, I want to measure thread context switching in c, How I can do that? Thanks, N.A.S

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Is demand paging enabled in linux kernels of Android?
by manty kuma March 19, 2014

March 19, 2014

Hi, Suppose I have an executable of size 60MB and I want to execute it on android(ARM), will 60MB be allocated to load the code onto the RAM? I remember studying about demand paging in Linux kernel. Is it relevant here? If yes, is it implemented in Linux kernels used in Android? Also, is there a config with which i can enable or disable the configs. I posted the same on SO. Answer it either place. Thank you. http://stackoverflow.com/questions/22499031/is-demand-paging-implemented-in… BR, Sandeep Kumar

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can direct ftrace to file
by loody March 19, 2014

March 19, 2014

hi all: usually I use cat /sys/kernel/debug/tracing/trace to look the ftrace result. Is it possible 1. direct trace to some file 2. enable ftrace 3. starting tracing what I interested 4. stop ftrace 5. open the file of #1 I directed that mean I can see whole trace log from #2 to #4 -- Regards,

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A new way to dive into the kernel!
by Mandeep Sandhu March 19, 2014

March 19, 2014

Came across this in Greg (KH)s G+ feed. http://eudyptula-challenge.org/ Thought I'd share it here too in case someone missed it. Looks like a fun and interesting way to start off doing stuff in the kernel! HTH, -mandeep

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[GSoC] universal list of syscalls
by Edson Ticona March 18, 2014

March 18, 2014

Hi My name is Edson Ticona. I was planning to participate in gsoc for strace in a project related to multiarch support, and they suggested me to check for this post http://thread.gmane.org/gmane.linux.kernel.cross-arch/21821 in the linux-arch mailing list so I think it might be better to help in the kernel as it would be useful not just to strace. What I have done so far is to write a system call for some architectures (x86, arm, sparc and microblaze) in order to understand how this part of the kernel works. I am doing the test with qemu. The post is pretty clear so maybe I could work in those archs and the tools for user space to expose this. Since this is not in any ideas list I would like some feedback and ask if someone could mentor this project. Cheers Edson

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Understanding of kernel stack print
by meenakshi aggarwal March 18, 2014

March 18, 2014

Hi, On reboot my system is showing kernel stack trace as : root@ds:~# reboot INIT: Sending processes the TERM signal INIT Stopping Dropbear SSH server: stopped /usr/sbin/dropbear (pid 2152) dropbear. Stopping network benchmark server: netserverstopped /usr/sbin/netserver (pid 2157) . Stopping system log daemon...0 Stopping kernel log daemon...0 Deconfiguring network interfaces... done. Sending all processes the TERM signal... Sending all processes the KILL signal... Unmounting remote filesystems... Deactivating swap... Unmounting local filesystems... Rebooting... Disabling non-boot CPUs ... BUG: scheduling while atomic: reboot/2210/0x00000002 Modules linked in: Preemption disabled at:[< (null)>] (null) Call Trace: [ebe09b20] [c0007094] show_stack+0x44/0x150 (unreliable) [ebe09b60] [c064f5f4] __schedule_bug+0x84/0x9c [ebe09b70] [c064c1c0] __schedule+0x510/0x5e0 [ebe09c80] [c064aea4] schedule_timeout+0x164/0x1d0 [ebe09cc0] [c064bb10] wait_for_common+0xd0/0x1b0 [ebe09d00] [c004db58] kthread_create_on_node+0xa8/0x140 [ebe09d70] [c00a42cc] _cpu_down+0x1ec/0x4e0 [ebe09de0] [c002d8a0] disable_nonboot_cpus+0x90/0x160 [ebe09e10] [c004044c] kernel_restart+0x1c/0x90 [ebe09e20] [c004069c] sys_reboot+0x1cc/0x250 [ebe09f40] [c000efe0] ret_from_syscall+0x0/0x3c --- Exception: c01 at 0xff17684 LR = 0x10000c00 BUG: scheduling while atomic: reboot/2210/0x00000002 Modules linked in: Preemption disabled at:[< (null)>] (null) Call Trace: [ebe09b90] [c0007094] show_stack+0x44/0x150 (unreliable) [ebe09bd0] [c064f5f4] __schedule_bug+0x84/0x9c [ebe09be0] [c064c1c0] __schedule+0x510/0x5e0 [ebe09cf0] [c064aea4] schedule_timeout+0x164/0x1d0 [ebe09d30] [c064bb10] wait_for_common+0xd0/0x1b0 [ebe09d70] [c00a42f8] _cpu_down+0x218/0x4e0 [ebe09de0] [c002d8a0] disable_nonboot_cpus+0x90/0x160 [ebe09e10] [c004044c] kernel_restart+0x1c/0x90 [ebe09e20] [c004069c] sys_reboot+0x1cc/0x250 [ebe09f40] [c000efe0] ret_from_syscall+0x0/0x3c --- Exception: c01 at 0xff17684 LR = 0x10000c00 and so on. Any kind of help will be appreciated. Also i want to know the significance of *0x84/0x9c* " __schedule_bug+*0x84/0x9c*"

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GSOC proposal
by sampriti neog March 18, 2014

March 18, 2014

To, The linux foundation I would like to participate in GOOGLE SUMMER OF CODE 2014 with your prestigious organization. I want to propose an idea regarding scanned files. My idea is to make a open source software that could scan a file directly into word document.This would be highly beneficial for direct editing.we dont need extra pdf to doc converter. For, making this i propose to use c++ language and incorporate the ocr technology to read the character individually and move them into the document.I would be really grateful if your organization take interest in my idea and suggest me more regarding my idea (if any). Looking forward to receive a quick and positive response from your side. Thanking you.

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Kernel Memory Growth
by Pietro Paolini March 18, 2014

March 18, 2014

Hello everyone, I am experiencing a problem using my Linux 2.6.33 and doing this networking test using ab, a tool from Apache which helps me to benchmark the performances of a website, actually I am using that as a tool for generate a lot of traffic and TCP connections. My topology is : [AB PC] <==> [LINUX] <==> [WEBSITE] I run ab like that ab -c 300 -n 20000 http://10.0.0.103/index.html and my problem is that after some time my system will reboot to a low memory condition, this is caused by the watchdog I have installed in my system, I tried to monitor my applications but I did not see any growth in the memory usage then I started to investigate if something is happening in the Kernel, using slab top I have got: OBJS ACTIVE USE OBJ SIZE SLABS OBJ/SLAB CACHE SIZE NAME 33392 33392 100% 1.00K 8348 4 33392K size-1024 3716 3716 100% 4.00K 3716 1 14864K size-4096 34238 33899 99% 0.20K 1802 19 7208K skbuff_head_cache 547 538 98% 8.00K 547 1 4376K size-8192 12488 12488 100% 0.27K 892 14 3568K nf_conntrack_c0ca4b0c 12990 12990 100% 0.12K 433 30 1732K size-128 2211 2211 100% 0.34K 201 11 804K inode_cache 11387 11368 99% 0.06K 193 59 772K size-64 41 41 100% 16.00K 41 1 656K size-16384 4 4 100% 128.00K 4 1 512K size-131072 2782 2702 97% 0.15K 107 26 428K dentry 4982 4957 99% 0.07K 94 53 376K sysfs_dir_cache 8814 8558 97% 0.03K 78 113 312K size-32 400 400 100% 0.50K 50 8 200K size-512 1540 1255 81% 0.11K 44 35 176K vm_area_struct 432 423 97% 0.30K 36 12 144K radix_tree_node The first line 33392 33392 100% 1.00K 8348 4 33392K size-1024 tell me that size-1024 is using quite a lot of memory, how can I understand who is using that memory ? Thanks in advance, Pietro

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Gosc proposal
by sampriti neog March 18, 2014

March 18, 2014

To, Kernelnewbies I would like to participate in GOOGLE SUMMER OF CODE 2014 with your prestigious organization. I want to propose an idea regarding music files. My idea is to make a song to lyrics converter using voice separation and then speech recognition idea so that any ongoing music can be converted to their wordings instantaneously without accessing internet for the lyrics. This project will be really helpful in our country because most of the people over here don't have access to internet and lyrics of all the songs aren't available. I would like to make the software using c/c++ coding. I would be really grateful if your organization take interest in my idea and suggest me more regarding my idea (if any). Looking forward to receive a quick and positive response from your side. Thanking you.

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GSOC proposal
by sampriti neog March 18, 2014

March 18, 2014

To, Kernelnewbies I would like to participate in GOOGLE SUMMER OF CODE 2014 with your prestigious organization. I want to propose an idea regarding music files. My idea is to make a song to lyrics converter using voice separation and then speech recognition idea so that any ongoing music can be converted to their wordings instantaneously without accessing internet for the lyrics. This project will be really helpful in our country because most of the people over here don't have access to internet and lyrics of all the songs aren't available. I would like to make the software using c/c++ coding. I would be really grateful if your organization take interest in my idea and suggest me more regarding my idea (if any). Looking forward to receive a quick and positive response from your side. Thanking you.

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