[sorry for a reply from -digest] feel free to critisize
Dominique Muller wrote: > A propos de la conférence d'hier soir, est-ce qu'il est prévu de faire un > résumé pour ceux comme moi, intéressé, mais n'ayant pu venir ? Evolution récente du noyau Linux Prof. Daniel P. Bovet Genève, Uni Mail, Amphi R060, mercredi 9 janvier 2002 à 20h30 talk notes [EMAIL PROTECTED] 11 jan 2002 Efficient OS ============ * same hardware, different OS * applications (even compiler) don't make a better OS * better kernel => better performance Two faces of a kernel --------------------- * interface: interaction with hardware from user space * performance: optimal use of available hardware (hardware evolves rapidly) How to obtain good performance ? -------------------------------- * there is no magic * many minor improvements make the difference Linux evolution =============== * new hardware => need for new software solutions (!<=) * a lot of redesign * experimental and stable kernels 2.2 -> 2.4 (3 good points) -------------------------- 1. TLB (translation lookaside buffer) TLB is used to reduce the number of calls to obtain mem. addr in RAM (x86: CR3 -> page directory -> page table -> page frame -> addr) improved TLB management during task (process) switching new flag for kernel threads 2. task scheduler when CPU "has nothing to do", it "runs" an idle process each process has a dynamic priority schedule() selects process with highest priority for a given CPU linux scheduling is not preemptive (kernel threads can't be interrupted) when schedule() should be called? process blocks (finishes?) process exec time has expired (time sharing) ~ 10-100 ms process with higher priority wakes up sched_yield() or sched_setscheduler() been called (more difficulties with multi-CPU machines, IPI: InterProcessorInterrupt) 3. memory (page frame) reclaiming (linux specific) several software caches caches size is not fixed (can grow until no more free memory) frame reclaiming = antidote from system freezing (lack of free memory) pages have 3 types of priorities (low -> high) 2.2 kernel swap out penalize a process which uses the largest nb. of pages (not good if memory is used effectively) 2.4 improvement 2 LRU(?) lists: active list (pages used frequently) and inactive list lists are updated dynamically (how to balance the lists?) <a href="http://bravo.ce.uniroma2.it/kernelhacking/en/index.html"> linux kernel hacking</a> -- Ivan Zimine | [EMAIL PROTECTED] Dpt. of Radiology | (+41 22) 372 70 70 Geneva University Hospitals | -- http://www-internal.alphanet.ch/linux-leman/ avant de poser une question. Ouais, pour se désabonner aussi.