On Tue, Feb 24, 2004 at 08:31:17AM -0800, prasanna wakhare wrote: > Hi all, > timer generates interruptes at HZ value we set this > value in timer0 . > this calculates to 1ms at which jiffies are incerment > in interrupt handler routine for timer interrupt! > if one have to generate same periodic interrupts at > extremly small delays like say 20 micro second ? > is there any way to do it in timer0 interrupt only we > can adjust the counter to generate at say 20 micro > second!or like that? > what are the ways to do have extremly low delay > interrupts! > thanks ! You can directly modify PIT controller on I/O port 0x40-0x43. 0x43 is the Mode Control Register, you must program it to accept binary-form-value and then insert new one: from: i8259.c outb_p(0x34,0x43); /* binary, mode 2, LSB/MSB, ch 0 */ outb_p(LATCH & 0xff , 0x40); /* LSB */ outb(LATCH >> 8 , 0x40); /* MSB */ you must modify LATCH value as you wish: #define LATCH ((CLOCK_TICK_RATE + HZ/2) / HZ) /* CLOCK_TICK_RATE is internal freq, HZ is 100 on linux, you must modify it, for example set LATCH to: #define LATCH ((CLOCK_TICK_RATE + 1000/2) / 1000) if you want 1000hz freq(one tick every ms). -- Kernelnewbies: Help each other learn about the Linux kernel. Archive: http://mail.nl.linux.org/kernelnewbies/ FAQ: http://kernelnewbies.org/faq/
