Jaswinder, On Sat, Sep 29, 2007 at 06:21:38PM +0530, Jaswinder Singh wrote: | Hello all, | | Please give contribution with open heart and give answers to max | questions as possible and give your reviews : I believe people were talking about you creating a FAQ entry in the RT Wiki page, at http://rt.wiki.kernel.org/index.php/Main_Page. | FAQ for realtime support in Linux Kernel | --------------------------------------- | Question Index | 1. Realtime Support questions | 2. Architecture questions | 3. Mailing list questions | 4. Realtime Patches questions | 5. Configuring/compiling questions | 6. Realtime samples/Performance questions | 7. Realtime Applications questions | 8. Maintainers questions | | Section 1 - Realtime Support questions | | Q1 What is realtime support | A1 | | Q2 How realtime works | A2 The RT-Preempt patch converts Linux into a fully preemptible | kernel. The magic is done with: | | * Making in-kernel locking-primitives (using spinlocks) preemptible | though reimplementation with rtmutexes: | * Critical sections protected by i.e. spinlock_t and rwlock_t are now | preemptible. The creation of non-preemptible sections (in kernel) is | still possible with raw_spinlock_t (same APIs like spinlock_t) | * Implementing priority inheritance for in-kernel spinlocks and | semaphores. For more information on priority inversion and priority | inheritance please consult Introduction to Priority Inversion | * Converting interrupt handlers into preemptible kernel threads: The | RT-Preempt patch treats soft interrupt handlers in kernel thread | context, which is represented by a task_struct like a common userspace | process. However it is also possible to register an IRQ in kernel | context. | * Converting the old Linux timer API into separate infrastructures for | high resolution kernel timers plus one for timeouts, leading to | userspace POSIX timers with high resolution. | | Q3 What is the procedure to add realtime support | A3 Download latest realtime preemption patch from | http://www.kernel.org/pub/linux/kernel/projects/rt/ then related get | vanilla kernel from http://kernel.org then patch , configure and | compile | | Section 2 - Architecture questions | | Q1 Which Architecture are supporting realtime and who is maintainer | A1 | | Q2 What is the procedure to support realtime in new architecture | A2 | | Section 3 - Mailing list questions | | Q1 realtime mailing list and archives | A1 http://www.mail-archive.com/linux-rt-users@xxxxxxxxxxxxxxx/ | | Q2 If I have some doubts or problems regarding realtime, do I need to | send mail in realtime mailing list or linux kernel mailing list or | both | A2 | | Section 4 - Realtime Patches questions | | Q1 Why I need to download realtime patches, If realtime support is in | Linux kernel | A1 | | Q2 Download latest realtime patches | A2 http://www.kernel.org/pub/linux/kernel/projects/rt/ | | Q3 Where can I post my realtime patches | A3 Please send patches for the CONFIG_PREEMPT_RT Patch Set to LKML and | put Ingo Molnar and Thomas Gleixner on CC. | | Please do not send clocksource and clockevents related patches against | the -rt patch. Make sure they apply against the latest -hrt-dyntick | patch. -hrt-dyntick might be a bit ahead of -rt at times, but the -rt | patch pulls -hrt-dyntick on a regular base. | | | Section 5 - Configuring/compiling questions | | Q1 How to enable/disable realtime support | A1 | | Q2 Change realtime support run time or statically | A2 | | Q3 Required parameters for configuring realtime kernel | A3 | | Q4 Optional parameters for configuring realtime kernel, but they | effect realtime performance | A4 | | Section 6 - Realtime samples/Performance questions | | Q1 What effects by realtime support and how much and samples to test | it and who maintains these samples | a. scheduling, task switching time | b. Interrupt latency | c. Interprocess communication | d. Filesystem | e. Device drivers | f. Network | g. X-Windows | | Section 7 - Realtime Applications questions | | Q1 List of realtime APIs | A1 | | Q2 How to write realtime applications | A2 | | Q3 Which programming languages are suitable for writing realtime applications | A3 | | Q4 Keep following things in mind while writing realtime applications | A4 Taking care of the following during the initial startup phase: | * Call directly from the main() entry the mlockall() call. | * Create all threads at startup time of the application, and touch | each page of the entire stack of each thread. Never start threads | dynamically during RT show time, this will ruin RT behavior. | * Never use system calls that are known to generate pagefaults, such | as fopen(). (Opening of files does the mmap() system call, which | generates a page-fault). | * Do not use 'compile time static arrays' without initializing them | directly after startup, before RT show time. | | | Q5 Do I need to recompile my applications to get realtime performance | A5 | | Section 8 - Maintainers questions | | Q1 Maintainers of realtime kernel patch | A1 | | On 9/29/07, Jaswinder Singh <jaswinderlinuxrt@xxxxxxxxx> wrote: | > hello all, | > | > I made sections in FAQ to make it more readable. | > | > Thank you, | > | > Jaswinder Singh. | > | - | To unsubscribe from this list: send the line "unsubscribe linux-rt-users" in | the body of a message to majordomo@xxxxxxxxxxxxxxx | More majordomo info at http://vger.kernel.org/majordomo-info.html ---end quoted text--- -- [ Luis Claudio R. Goncalves Red Hat - Realtime Team ] [ Fingerprint: 4FDD B8C4 3C59 34BD 8BE9 2696 7203 D980 A448 C8F8 ] - To unsubscribe from this list: send the line "unsubscribe linux-rt-users" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
