On Fri, Feb 10, 2012 at 8:39 PM, Peter Zijlstra <a.p.zijlstra@xxxxxxxxx> wrote: > On Sun, 2012-02-05 at 13:46 +0200, Gilad Ben-Yossef wrote: >> > /* >> > * Cause all memory mappings to be populated in the page table. >> > * Specifying this when entering dataplane mode ensures that no future >> > * page fault events will occur to cause interrupts into the Linux >> > * kernel, as long as no new mappings are installed by mmap(), etc. >> > * Note that since the hardware TLB is of finite size, there will >> > * still be the potential for TLB misses that the hypervisor handles, >> > * either via its software TLB cache (fast path) or by walking the >> > * kernel page tables (slow path), so touching large amounts of memory >> > * will still incur hypervisor interrupt overhead. >> > */ >> > #define DP_POPULATE 0x8 >> >> hmm... I've probably missed something, but doesn't this replicate >> mlockall (MCL_CURRENT|MCL_FUTURE) ? > > Never use mlockall() its a sign you're doing it wrong, also his comment > seems to imply MCL_FUTURE isn't required. > My current understanding is that if I have a real time task and wish it have a deterministic performance time, you should call mlockall() to lock the program data and text into physical memory so that a less often taken branch or access to a new data region will not result in a page fault. You still have to worry about TLB misses on non hardware page table walk architecture, but at least everything is in the page tables If there is a better way to do this? I'm always happy to learn new ways to do things. :-) Thanks, Gilad -- Gilad Ben-Yossef Chief Coffee Drinker gilad@xxxxxxxxxxxxx Israel Cell: +972-52-8260388 US Cell: +1-973-8260388 http://benyossef.com "If you take a class in large-scale robotics, can you end up in a situation where the homework eats your dog?" -- Jean-Baptiste Queru -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href