November 2014 - kernelnewbies@kernelnewbies.org

[PATCH] drivers: Fix typos in rt2800lib.c and oxu210hp-hcd.c
by Nicholas Krause Nov. 10, 2014

Nov. 10, 2014

Changes a typo of fimxe to fixme in the files,rtl2800lib.c and oxu210hp-hcd.c. Signed-off-by: Nicholas Krause <xerofoify(a)gmail.com> --- drivers/net/wireless/rt2x00/rt2800lib.c | 2 +- drivers/usb/host/oxu210hp-hcd.c | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/net/wireless/rt2x00/rt2800lib.c b/drivers/net/wireless/rt2x00/rt2800lib.c index 9f57a2d..14d6a5d 100644 --- a/drivers/net/wireless/rt2x00/rt2800lib.c +++ b/drivers/net/wireless/rt2x00/rt2800lib.c @@ -2843,7 +2843,7 @@ static void rt2800_config_channel_rf55xx(struct rt2x00_dev *rt2x00dev, ep_reg = 0x2; } else { rt2800_rfcsr_write(rt2x00dev, 10, 0x97); - /* FIMXE: RF11 overwrite */ + /* FIXME: RF11 overwrite */ rt2800_rfcsr_write(rt2x00dev, 11, 0x40); rt2800_rfcsr_write(rt2x00dev, 25, 0xBF); rt2800_rfcsr_write(rt2x00dev, 27, 0x42); diff --git a/drivers/usb/host/oxu210hp-hcd.c b/drivers/usb/host/oxu210hp-hcd.c index 4fe79a2..2ef5d59 100644 --- a/drivers/usb/host/oxu210hp-hcd.c +++ b/drivers/usb/host/oxu210hp-hcd.c @@ -2677,7 +2677,7 @@ static int oxu_reset(struct usb_hcd *hcd) INIT_LIST_HEAD(&oxu->urb_list); oxu->urb_len = 0; - /* FIMXE */ + /* FIXME */ hcd->self.controller->dma_mask = NULL; if (oxu->is_otg) { -- 1.9.1

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viewing pr_debug messages
by Kevin Wilson Nov. 9, 2014

Nov. 9, 2014

I am using journalctl -kf or journalctl -k to see kernel log messages. However, messages of "pr_debug" are not shown by this commands. Is there some way to view pr_debug kernel messages with journalctl -k ? regards, Kevin

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lots of connections in SYN_RECV state
by Puneet Agarwal Nov. 8, 2014

Nov. 8, 2014

Hello, I have a couple of servers, for the past few days I am seeing lots of connections in SYN_RECV state in netstat commands output. Is there a solution to this problem? Thanks and Regards Puneet

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Eudyptula challenge status
by Ramon Fried Nov. 7, 2014

Nov. 7, 2014

Hey all. Tasks are pending for a long time. Anyone has Info regarding the queue? Thanks. Ramon

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broken network connection
by Grzegorz Dwornicki Nov. 7, 2014

Nov. 7, 2014

Hi I have a big interest in how kernel handles this situaction. Lets assume that we have two hosts: host 1 and host 2 and on host 1 I have started this command: nc -l -p 4444 on host 2 I have started this command (2 means IP addres of second host here!): nc 2 4444 Now i can send msgs betweem them. In time I have decided to end connection. To do this I'm using ctrl+c on host 2. What functions are called to clean broken socket on host 1? What functions are called to clean up socket on host 2? Grzegorz.

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Re:Re: Why page fault handler behaved this way? Please help!
by 秦弋戈 Nov. 5, 2014

Nov. 5, 2014

Hello, Thank you very much for helping me. Before I see your reply, I enlarged my program and I saw more page faults in code segment. Now I know there is something called fault-around. I read the Chapter 16 of the ULK which introduces file access. I started to know a technique called read-ahead from this chapter. So what's the difference or relationship between fault-around and read-ahead? I think they are used in different areas (layers) but have the same idea. Am I right? Best regards At 2014-11-04 21:13:56, "Kirill A. Shutemov" <kirill(a)shutemov.name> wrote: >On Tue, Nov 04, 2014 at 07:41:08PM +0700, Mulyadi Santosa wrote: >> Hello... >> >> how big is your binary anyway? >> >> from your log, if my calculation is right, your code segment is around 330 >> KiB. But bear in mind, that not all of them are your code. There are other >> code like PLT, function prefix and so on. >> >> Also, even if your code is big, are you sure all of them are executed? >> Following 20/80 principle, most of the time, when running an application, >> only 20% portion of the application are really used/executed during 80% of >> application lifetime. The rest, it might untouched at all. >> >> >> On Thu, Oct 30, 2014 at 2:10 PM, 秦弋戈 <michaelbest002(a)126.com> wrote: >> >> > >> > >> > >> > Dear all, >> > >> > >> > I am a kernel newbie who want's to learn more about memory management. >> > Recently I'm doing some experiment on page fault handler. There happened >> > something that I couldn't understand. >> > >> > >> > From reading the book Understanding the Linux Kernel, I know that the >> > kernel loads a page as late as possible. It's only happened when the >> > program has to reference (read, write, or execute) a page yet the page is >> > not in memory. >> > >> > >> > However, when I traced all page faults in my test program, I found >> > something strange. My test program is large enough, but there are only two >> > page faults triggered in the code segment of the program, while most of the >> > faults are not in code segment. >> > >> > >> > At first I thought that perhaps the page is not the normal 4K page. Thus I >> > turned off the PAE support in the config file. But the log remains >> > unchanged. >> > >> > >> > So why are there only 2 page faults in code segment? It shouldn't be like >> > this in my opinion. Please help me. > >We have "faultaround" feature in recent kernel which tries to map 64k with >one page fault if the pages are already in page cache. There's handle in >debugfs to disable the feature, if you want to play with this. > >> > The attachment is my kernel log. Limited by the mail size, I couldn't >> > upload my program, but I believe that the log is clear enough. >> > >> > >> > Thank you very much. >> > Best regards >> > >> > >> > _______________________________________________ >> > Kernelnewbies mailing list >> > Kernelnewbies(a)kernelnewbies.org >> > http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies >> > >> > >> >> >> -- >> regards, >> >> Mulyadi Santosa >> Freelance Linux trainer and consultant >> >> blog: the-hydra.blogspot.com >> training: mulyaditraining.blogspot.com > >-- > Kirill A. Shutemov

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RT Kernel compile and install help needed.
by Chanchal Paul Nov. 4, 2014

Nov. 4, 2014

Hi, I am fairly new to kernel compilation and installation process, still i managed to learn from Kernelnewbies and RT-wiki and managed to patch 3.12.14 vanilla kernel with rt patch 3.14.12. Then I followed the steps and installed rt-kernel in my lubuntu vm. While doing "make menuconfig" i selected preemtion model as BASIC-RT from processor type and features option. It worked. Now my confusion arises when i see my uname -a string as "Linux paul-lubuntu 3.14.12-rt9 #2 SMP PREEMPT Tue Oct 28 13:30:27 UTC 2014 x86_64 x86_64 x86_64 GNU/Linux" which indicated that i have a preemptive kernel installed. but the c program from " https://rt.wiki.kernel.org/index.php/RT_PREEMPT_HOWTO" for "Runtime detection of an RT-PREEMPT Kernel" only prints "this is a vanilla kernel". So, my question is am I running a vanilla kernel or a real-time kernel? If I am not then what are the steps to properly install a real-time kernel? Thanking you for giving attention to my mail.

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Why page fault handler behaved this way? Please help!
by 秦弋戈 Nov. 4, 2014

Nov. 4, 2014

Dear all, I am a kernel newbie who want's to learn more about memory management. Recently I'm doing some experiment on page fault handler. There happened something that I couldn't understand. From reading the book Understanding the Linux Kernel, I know that the kernel loads a page as late as possible. It's only happened when the program has to reference (read, write, or execute) a page yet the page is not in memory. However, when I traced all page faults in my test program, I found something strange. My test program is large enough, but there are only two page faults triggered in the code segment of the program, while most of the faults are not in code segment. At first I thought that perhaps the page is not the normal 4K page. Thus I turned off the PAE support in the config file. But the log remains unchanged. So why are there only 2 page faults in code segment? It shouldn't be like this in my opinion. Please help me. The attachment is my kernel log. Limited by the mail size, I couldn't upload my program, but I believe that the log is clear enough. Thank you very much. Best regards

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Why does register_block release a bdev_inode instance at the end?
by Rock Lee Nov. 4, 2014

Nov. 4, 2014

Hi, all: It has been known that all inodes that represent block devices are kept on the bdev pseudo-filesystem.And I thought that a bdev_inode instance is generated when the function of register_disk is called.But why does register_disk release a bdev_inode instance by calling blkdev_put at the end? BTW, my kernel is linux-2.6.32. RegardsRock Lee

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Healthy cpu operating temperature range
by Puneet Agarwal Nov. 4, 2014

Nov. 4, 2014

Hello, I am having some servers which serves http traffic at high qps. Strangely for past few days I am seeing latency going up. I am worried if these CPU temperatures can be the reason. Core 0: +74.0°C (high = +90.0°C, crit = +100.0°C) Core 1: +78.0°C (high = +90.0°C, crit = +100.0°C) Core 9: +73.0°C (high = +90.0°C, crit = +100.0°C) Core 10: +81.0°C (high = +90.0°C, crit = +100.0°C) coretemp-isa-0004 Adapter: ISA adapter Core 0: +81.0°C (high = +90.0°C, crit = +100.0°C) Core 1: +80.0°C (high = +90.0°C, crit = +100.0°C) Core 9: +81.0°C (high = +90.0°C, crit = +100.0°C) Core 10: +81.0°C (high = +90.0°C, crit = +100.0°C) top command gives load average, Load: 12.03, 6.76, 4.44 Processor specification sheet says Tcase is 63.1°C, and the sensor tool states 90°C as high. This is not letting me believe which one is correct to pick and what is the ideal temperature range for CPU to run. Thanks and Regards Puneet

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