http://blog.gmane.org/gmane.linux.kernel.kernelnewbies hourly 1 1901-01-01T00:00+00:00 http://gmane.org/img/gmane-25t.png http://gmane.org http://comments.gmane.org/gmane.linux.kernel.kernelnewbies/44597 <pre>Hi, I am trying to write small program to get CPU usage for a particular process. My logic is to read user, nice, system, idle values from /proc/stat. Then read user and system time from /proc/&lt;pid&gt;/stat. Then wait for some time and again read same values. After that I am doing following calculations CPU% = (no_of_processor * (process_cpu_usage2-process_cpu_usage1) * 100 ) / (total_cpu_usage2-total_cpu_usage1) When I compare my output with top, it looks like correct, but sometimes it is more than 100. Is my logic correct here ? Please correct me if I am worng. Regards, Rahul _______________________________________________ Kernelnewbies mailing list Kernelnewbies&lt; at &gt;kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies </pre> Rahul Bedarkar 2013-05-20T10:05:28 http://comments.gmane.org/gmane.linux.kernel.kernelnewbies/44590 <pre>Dear all, Is there any uboot config option in to print boot sequence with time prefixes similar to kernel option CONFIG_PRINTK ? Thanks &amp; Regards Dhyan _______________________________________________ Kernelnewbies mailing list Kernelnewbies&lt; at &gt;kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies </pre> Dhyan 2013-05-20T07:07:25 http://comments.gmane.org/gmane.linux.kernel.kernelnewbies/44589 <pre>Folks, Can you please suggest me some nice books or tutorials that concentrates more on the x86_64 assembly programming using GNU assembler. Unfortunately, I haven't done any assembly programming for the last seven years, but my current job requires me to analyse kernel crashes and a lot of them (probably due to widespread use of x86-64 architecture) originate on x86-64 machines and quite often disassembling is the last resort to inspect the function parameters, stack frames etc. There seem to tons of books, tutorials, assemblers available over the internet, but I'm looking for something that can give me jumpstart on x86_64 assembly, specially in Linux environment. Recently, While browsing, I've found these two: 1: x86_64 ABI (System V Application Binary Interface, AMD64 Architecture Processor Supplement) - 2: x86-64 Machine-Level Programming - Randal and David Appreciate a lot, If you can recommend me your favourite text book on x86-64 assembly or any such reference material. Thanks, -Amit </pre> amit mehta 2013-05-20T06:13:28 http://comments.gmane.org/gmane.linux.kernel.kernelnewbies/44586 <pre>Hello, The Select system call has given the timeout of 100 msec and but its expired after 115 msecs. I have no fds to read, and just wanted to use select as the timer to timeout and so some stuff after the timeout happen. code: #include &lt;stdio.h&gt; #include &lt;sys/stat.h&gt; #include &lt;sys/types.h&gt; #include &lt;sys/select.h&gt; main() { int ret; struct timeout tv; tv.tv_sec = 0; tv.tv_usec = 100000; while (1) { ret = select(5, 0, 0, 0, &amp;tv); if (ret == 0) { struct timeval t; gettimeofday(&amp;t, 0); printf("sec = %d-usec = %d\n", t.tv_sec, t.tv_usec); } } } my kernel is older, 2.6.23. thanks, </pre> devendra.aaru 2013-05-17T11:59:08 http://comments.gmane.org/gmane.linux.kernel.kernelnewbies/44581 <pre>Hi, This is really not a linux kernel question, but I guess there are enough OS specialists on this thread that someone can point me in the right direction. Some context ---------------------- On normal hardware machines its possible to change the page table flags to make a particular 4K page area as readonly or readwrite. This is generally used for protecting against memory corruptions. Now even if you have READONLY flags set in the page table, its possible to change the control register of a particular cpu (in a multicore system) such that, that cpu will not cause a fault/trap if you try to modify the contents of the page. What this means is let's say I have 4 cpus, and I change the control register on cpu-1, only cpu-1 will see the page as readwrite and others will see it as readonly. I've seen that this behavior is honoured in virtualised vmware environments too, so I'm assuming that this cpu behavior is getting simulated somehow. My problem is that I want to simulate the same behavior in userspace, where my 4 cpus map to 4 pthreads. I change the permissions of my memory area using mprotect() but then I also want to have a similar capability where I can flip/change something in one of the threads and that thread should be able to modify the region, while for other pthreads it is still a readonly page. Any suggestions how vmware or other virtualised environments do this, or is this even possible ? Any pointers to the code is appreciated. (Sorry no locking/synchronisation solutions pls). </pre> Manish Katiyar 2013-05-15T22:31:33 http://comments.gmane.org/gmane.linux.kernel.kernelnewbies/44560 <pre>Hello, As far as I know, Wake On Lan is disabled by default in Linux. Now I try this on p2p1: ethtool -i p2p1 ... driver: r8169 ... ethtool p2p1 .. Wake-on: g ... this means, according to the man, that Wake on Lan is enabled for MagicPacket packets on p2p1 Now I looked in the code of the driver and I cannot see anywhere a call to pci_enable_wake(); see drivers/net/ethernet/realtek/r8169.c So any ideas how come that the Wake on Lan is enabled for this driver after boot ? rgs, Andy </pre> Andy Johnson 2013-05-14T12:20:36 http://comments.gmane.org/gmane.linux.kernel.kernelnewbies/44555 <pre>Hello,       I have an ARM platform board. I need to change the smp_affinity of PCIe MSI interrupt. The drivers/pci/msi.c file does not any function for changing the smp_affinity. Any pointers as to how to change the affinity would be very helpful. Regards, Amit. _______________________________________________ Kernelnewbies mailing list Kernelnewbies&lt; at &gt;kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies </pre> Amit Mahadik 2013-05-14T04:53:40 http://comments.gmane.org/gmane.linux.kernel.kernelnewbies/44552 <pre>Hi, How to decode the stats thrown by the oom killer ? Is there any good in depth documentation out there for this ? Node 0 DMA per-cpu: cpu 0 hot: high 0, batch 1 used:0 cpu 0 cold: high 0, batch 1 used:0 Node 0 DMA32 per-cpu: cpu 0 hot: high 186, batch 31 used:25 cpu 0 cold: high 62, batch 15 used:49 Node 0 Normal per-cpu: empty Node 0 HighMem per-cpu: empty Free pages: 3532kB (0kB HighMem) Active:4471 inactive:4099 dirty:1 writeback:0 unstable:0 free:883 slab:14568 mapped-file:542 mapped-anon:8049 pagetables:1033 Node 0 DMA free:368kB min:44kB low:52kB high:64kB active:0kB inactive:0kB present:9700kB pages_scanned:0 all_unreclaimable? yes lowmem_reserve[]: 0 632 632 632 Node 0 DMA32 free:3164kB min:3192kB low:3988kB high:4788kB active:17884kB inactive:16396kB present:647348kB pages_scanned:920345 all_unreclaims lowmem_reserve[]: 0 0 0 0 Node 0 Normal free:0kB min:0kB low:0kB high:0kB active:0kB inactive:0kB present:0kB pages_scanned:0 all_unreclaimable? no lowmem_reserve[]: 0 0 0 0 Node 0 HighMem free:0kB min:128kB low:128kB high:128kB active:0kB inactive:0kB present:0kB pages_scanned:0 all_unreclaimable? no lowmem_reserve[]: 0 0 0 0 Node 0 DMA: 30*4kB 7*8kB 2*16kB 1*32kB 0*64kB 1*128kB 0*256kB 0*512kB 0*1024kB 0*2048kB 0*4096kB = 368kB Node 0 DMA32: 81*4kB 53*8kB 65*16kB 23*32kB 0*64kB 1*128kB 0*256kB 1*512kB 0*1024kB 0*2048kB 0*4096kB = 3164kB Node 0 Normal: empty Node 0 HighMem: empty 8602 pagecache pages Swap cache: add 21037, delete 12988, find 320/473, race 0+1 Free swap = 940120kB Total swap = 1020116kB Out of memory: Killed process 2024, UID 51, (sendmail). Regards. </pre> Prashant Shah 2013-05-14T13:40:44 http://comments.gmane.org/gmane.linux.kernel.kernelnewbies/44548 <pre>Hi there, I learned, e.g. from here that user space device drivers are indeed possible: http://www.makelinux.net/ldd3/chp-2-sect-9 Are there serious user space drivers in Linux? Could you name a few? Or, is this just for hacking a driver for your home-made hardware? - Gergely </pre> Gergely Buday 2013-05-13T19:52:36 http://comments.gmane.org/gmane.linux.kernel.kernelnewbies/44545 <pre>Hi, I was under the impression that when the bio comes to a block device driver its size is variable. But, after writing a block device driver i realized that such is not the case and it always is 4096. Does this mean that by default if i don't use any merge function the bio will always have size 4096(meaning it will have only 1 page!!!!). Regards, Neha _______________________________________________ Kernelnewbies mailing list Kernelnewbies&lt; at &gt;kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies </pre> neha naik 2013-05-13T15:32:24 http://comments.gmane.org/gmane.linux.kernel.kernelnewbies/44540 <pre>Hi all, Supposing i create a file of size 10K, it will occupy 2 blocks (4K each). Now if i want to read only 1 block from it how can i do it? read(fd, buf, 4096) ; would this mean i would read the first block and all its contents? Thanks </pre> shampavman 2013-05-13T08:05:54 http://comments.gmane.org/gmane.linux.kernel.kernelnewbies/44538 <pre>Hello, I have a question about git patches. When I run git log include/linux/skbuff.h and page down till the end, I reach 1da177e Linux-2.6.12-rc2 (I do it on the net-next tree.) git show 1da177e gives: Author: Linus Torvalds &lt;torvalds&lt; at &gt;ppc970.osdl.org&gt; Date: Sat Apr 16 15:20:36 2005 -0700 Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip! So this is the initial patch from 2005. Now, does it mean that prior to this patch all patches were not handled by git ? or was there some merging from an old tree to a new tree where history of git patches was removed in the new tree ? regards, Kevin </pre> Kevin Wilson 2013-05-13T07:51:33 http://comments.gmane.org/gmane.linux.kernel.kernelnewbies/44537 <pre>In a system with 3:1 split, the ZONE_NORMAL with a size of 896MB is permanently mapped to the kernel address space.This leaves a 128MB free space in the Kernel address space and according to my understanding, the ZONE_HIGHMEM pages are mapped temporarily to this 128MB part. If the system actually had a 4GB physical memory you will be mapping(not smultaneously) the HIHGMEM part- which is roughly 3.2GB - to this 128MB part. If that was the case Kernel would have to frequently access HIHGMEM which implicates a frequent change in temporaty mapping and that in my view is a penalty. So what was the reason why ZONE_NORMAL fixed at 896MB and not something really lower? </pre> Paul Davies C 2013-05-11T03:32:07 http://comments.gmane.org/gmane.linux.kernel.kernelnewbies/44534 <pre>Hello All, I want to some process that too not of Intel. Does anyone know an site that can help me? And on what basis should i compare the processor? Thanks Rob _______________________________________________ Kernelnewbies mailing list Kernelnewbies&lt; at &gt;kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies </pre> Robert Clove 2013-05-10T07:21:06 http://comments.gmane.org/gmane.linux.kernel.kernelnewbies/44531 <pre>Hi All, Is there a kernel routine ( not a system call ) that a kernel module can call to "lock" all of the pages of a particular VMA of a user process that is using the driver ? </pre> Buland Kumar Singh 2013-05-09T16:55:54 http://comments.gmane.org/gmane.linux.kernel.kernelnewbies/44529 <pre>Hi all, Any idea for what do we need gflags of net_device? I believe gflags stand for global flags (though the header file, netdevice.h, does not say so explicitly). I see that they are initialized only in __dev_change_flags() , in net/core/dev.c, in But it is not clear what is their meaning. Any ideas? can someone elaborate on this ? rgs, Andy </pre> Andy Johnson 2013-05-09T12:02:02 http://comments.gmane.org/gmane.linux.kernel.kernelnewbies/44525 <pre>hi all: the codes is: extern inline unsigned char get_fs_byte(const char * addr) { unsigned register char _v; __asm__ ("movb %%fs:%1,%0":"=r" (_v):"m" (*addr)); return _v; } What's the meaning of "%%fs" ? Is " __asm__ ("movb %1,%0":"=r" (_v):"m" (*addr));" not ok? Thank you. _______________________________________________ Kernelnewbies mailing list Kernelnewbies&lt; at &gt;kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies </pre> lx 2013-05-09T10:04:16 http://comments.gmane.org/gmane.linux.kernel.kernelnewbies/44523 <pre> Here is the OOM trace header : Out of memory: Kill process 5374 (min_free_kbytes) score 944 or sacrifice child Killed process 5374 (min_free_kbytes) total-vm:30495360kB,anon-rss:20155328kB, file-rss:64kB min_free_kbytes invoked oom-killer: gfp_mask=0x200da, order=0, oom_score_adj=0 min_free_kbytes cpuset=/ mems_allowed=0 ------------------ I understand that in this case free pages has gone below min_pages(1). Couple of questions based on these 4 lines : (1) I googled a lot but I am not able to find the meaning of 'score 994' , anon-rss and file-rss ? (2) In my understanding gfp_mask is relevant here to know from which Zone the memory allocation was tried , but failed - right ? (3) What do order and oom_score_adj signify here ? Regards, Shraddha (1) http://dd.qc.ca/people.redhat.com/kernel/min_free_kbytes.html </pre> Shraddha Kamat 2013-05-08T17:57:40 http://comments.gmane.org/gmane.linux.kernel.kernelnewbies/44519 <pre>Hello,       Following is the output of cat /proc/interrupts                       CPU0       CPU1       CPU2 200:       9634          0          0  PCIe0-MSI  eth0 I want to change the processor affinity of the above PCIe interrupt By executing command echo 2 &gt; /proc/irq/200/smp_affinity I get the following error sh: write error: Input/output error Even after changing the file permissions I have the same problem. I would like to know how to change the affinity of the above virtual interrupt?? Regards, Amit. _______________________________________________ Kernelnewbies mailing list Kernelnewbies&lt; at &gt;kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies </pre> Amit Mahadik 2013-05-08T12:05:09 http://comments.gmane.org/gmane.linux.kernel.kernelnewbies/44517 <pre>Any good tutorial for analyzing kernel call traces ? I want to know what is the meaning of everything that appears in the call trace and get to the exact cause of the problem. Thanks for the noble cause of sharing knowledge. Regards, Shraddha </pre> Shraddha Kamat 2013-05-08T07:16:23 http://comments.gmane.org/gmane.linux.kernel.kernelnewbies/44514 <pre>Hi： As I know .the /dev/tty is the current task's tty , which is stored to current-&gt;tty , My question is when does this value is assgined to current-&gt;tty ? Thanks! _______________________________________________ Kernelnewbies mailing list Kernelnewbies&lt; at &gt;kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies </pre> Hatte John 2013-05-08T04:21:32 Search the mailing list at Gmane query http://search.gmane.org/?group=$group=gmane.linux.kernel.kernelnewbies