High-res-timers part 1 (core)
Subsystems (4)
PATCH 1/1 High-res-timers part 1 (core)
This patch supplies the core changes to implement high resolution timers. Mostly it changes the timer list from the multi stage hash (or cascade) list to a single stage hash list. This change makes it easy to configure the list size for those who are concerned with performance. It also eliminates the "time out" for the cascade operation every 512 jiffies, thus eliminating possible long preemption times.
It also adds a sub jiffie word to the timer structure to allow timers to exist between jiffies. However, to support the sub jiffie timers, work needs to be done in the platform code for each arch. The platform work for the i386 arch follows in part 2. To prevent requests from non-existant code for sub jiffies stuff, these parts of this patch are disabled with the IF_HIGH_RES() macro which depends on CONFIG_HIGH_RES_TIMERS which will be defined for each platform as they supply the needed code.
With this patch applied, the system should boot and run much as it does prior to the patch.
Signature · 5 lines
George Anzinger [email protected] High-res-timers: http://sourceforge.net/projects/high-res-timers/ Preemption patch: http://www.kernel.org/pub/linux/kernel/people/rml
include/linux/hrtime.h +155 -0
@@ -0,0 +1,155 @@ +#ifndef _HRTIME_H +#define _HRTIME_H + + + +/* +* This file is the glue to bring in the platform stuff. +* We make it all depend on the CONFIG option so all archs +* will work as long as the CONFIG is not set. Once an +* arch defines the CONFIG, it had better have the +* asm/hrtime.h file in place. +*/ +/* +* This gets filled in at init time, either static or dynamic. +* Someday this will be what NTP fiddles with. +* Do we need the scale here? I don't think so, as long as we +* do percentage offsets for NTP. +*/ +struct timer_conversion_bits { +unsigned long _arch_to_usec; +unsigned long _arch_to_nsec; +unsigned long _usec_to_arch; +unsigned long _nsec_to_arch; +long _cycles_per_jiffies; +unsigned long _arch_to_latch; +}; +extern struct timer_conversion_bits timer_conversion_bits; +/* +* The following four values are not used for machines +* without a TSC. For machines with a TSC they +* are caculated at boot time. They are used to +* calculate "cycles" to jiffies or usec. Don't get +* confused into thinking they are simple multiples or +* divisors, however. +*/ +#define arch_to_usec timer_conversion_bits._arch_to_usec +#define arch_to_nsec timer_conversion_bits._arch_to_nsec +#define usec_to_arch timer_conversion_bits._usec_to_arch +#define nsec_to_arch timer_conversion_bits._nsec_to_arch +#define cycles_per_jiffies timer_conversion_bits._cycles_per_jiffies +#define arch_to_latch timer_conversion_bits._arch_to_latch + +#include <linux/config.h> +#ifdef CONFIG_HIGH_RES_TIMERS +#include <asm/hrtime.h> +/* +* The schedule_next_int function is to be defined by the "arch" code +* when an "arch" is implementing the high-res part of POSIX timers. +* The actual function will be called with the offset in "arch" (parm 2) +* defined sub_jiffie units from the reference jiffie boundry (parm 1)to +* the next required sub_jiffie timer interrupt. This value will be -1 +* if the next timer interrupt should be the next jiffie value. The +* "arch" code must determine how far out the interrupt is, based on +* current jiffie, sub_jiffie time and set up the hardware to interrupt +* at that time. It is possible that the time will already have passed, +* in which case the function should return true (no interrupt is +* needed), otherwise the return should be 0. The third parameter is the +* "always" flag which says that the code needs an interrupt, even if the +* time has passed. In this case a "close" in time should be used to +* generate the required interrupt. The sub_jiffie interrupt +* should just call do_timer(). If the interrupt code ususally does stuff +* each jiffie, a flag should be kept by the jiffies update code to +* indicate that a new jiffie has started. This flag is to keep this code +* from being executed on the sub jiffie interrupt. +*/ +#ifndef schedule_next_int +#define schedule_next_int (s,d,a) 0 +#undef CONFIG_HIGH_RES_TIMERS +#endif // schedule_next_int +/* +* The sub_jiffie() macro should return the current time offset from the latest +* jiffie. This will be in "arch" defined units and is used to determine if +* a timer has expired. Since no sub_expire value will be used if "arch" +* has not defined the high-res package, 0 will work well here. +* +* In addition, to save time if there is no high-res package (or it is not +* configured), we define the sub expression for the run_timer_list. +*/ + +#ifndef sub_jiffie +#undef CONFIG_HIGH_RES_TIMERS +#define sub_jiffie () 0 +#endif // sub_jiffie + +/* +* The high_res_test() macro should set up a test mode that will do a +* worst case timer interrupt. I.e. it may be that a call to +* schedule_next_int() could return -1 indicating that the time has +* already expired. This macro says to set it so that schedule_next_int() +* will always set up a timer interrupt. This is used during init to +* calculate the worst case loop time from timer set up to int to +* the signal code. + +* high_res_end_test() cancels the above state and allows the no +* interrupt return from schedule_next_int() +*/ +#ifndef high_res_test +#define high_res_test () +#define high_res_end_test () +#endif + + +#define IF_HIGH_RES (a) a + +#else /* CONFIG_HIGH_RES_TIMERS */ +#define IF_HIGH_RES (a) +#define nsec_to_arch_cycles (a) 0 + +#endif /* CONFIG_HIGH_RES_TIMERS */ + +/* +* Here is an SMP helping macro... +*/ +#ifdef CONFIG_SMP +#define if_SMP (a) a +#else +#define if_SMP (a) +#endif +/* +* These should have been defined in the platform hrtimers.h +* If not (or HIGH_RES_TIMERS not configured) define the default. +*/ +#ifndef update_jiffies +extern u64 jiffies_64; +#define update_jiffies () (*(u64 *)&jiffies_64)++ +#endif +#ifndef new_jiffie +#define new_jiffie () 0 +#endif +#ifndef schedule_next_int +#define schedule_next_int (a,b,c) +#endif +/* +* If we included a high-res file, we may have gotten a more efficient +* u64/u32, u64%u32 routine. The one in div64.h actually handles a +* u64 result, something we don't need, and, since it is more expensive +* arch porters are encouraged to implement the div_long_long_rem(). +* +* int div_long_long_rem(u64 dividend,int divisor,int* remainder) +* which returns dividend/divisor. +* +* Here we provide default code for those who, for what ever reason, +* have not provided the above. +*/ +#ifndef div_long_long_rem +#include <asm/div64.h> + +#define div_long_long_rem (dividend,divisor,remainder) ({ \ + u64 result = dividend; \ + *remainder = do_div(result,divisor); \ + result; }) + +#endif /* ifndef div_long_long_rem */ + +#endif /* _HRTIME_H */
include/linux/signal.h +29 -0
@@ -219,6 +219,35 @@ }extern long do_sigpending (void *,unsigned long ); +/* +* We would like the asm/signal.h code to define these so that the using +* function can call do_signal(). In loo of that, we define a genaric +* version that pretends that do_signal() was called and delivered a signal. +* To see how this is used, see nano_sleep() in timer.c and the i386 version +* in asm_i386/signal.h. +*/ +#ifndef PT_REGS_ENTRY +#define PT_REGS_ENTRY (type,name,p1_type,p1, p2_type,p2) \ +type name(p1_type p1,p2_type p2)\ +{ +#endif +#ifndef _do_signal +#define _do_signal () 1 +#endif +#ifndef NANOSLEEP_ENTRY +#define NANOSLEEP_ENTRY (a) asmlinkage long sys_nanosleep( struct timespec* rqtp, \ + struct timespec * rmtp) \ +{ a +#endif +#ifndef CLOCK_NANOSLEEP_ENTRY +#define CLOCK_NANOSLEEP_ENTRY (a) asmlinkage long sys_clock_nanosleep( \ + clockid_t which_clock, \ + int flags, \ + const struct timespec *rqtp, \ + struct timespec *rmtp) \ +{ a + +#endif #ifndef HAVE_ARCH_GET_SIGNAL_TO_DELIVER struct pt_regs ;
include/linux/time.h +20 -6
@@ -1,7 +1,7 @@#ifndef _LINUX_TIME_H#define _LINUX_TIME_H -#include <asm/param.h> +#include <linux/param.h> #include <linux/types.h> #ifndef _STRUCT_TIMESPEC
@@ -38,6 +38,19 @@*/ #define MAX_JIFFY_OFFSET ((~0UL >> 1)-1) +/* Parameters used to convert the timespec values */ +#ifndef USEC_PER_SEC +#define USEC_PER_SEC (1000000L) +#endif + +#ifndef NSEC_PER_SEC +#define NSEC_PER_SEC (1000000000L) +#endif + +#ifndef NSEC_PER_USEC +#define NSEC_PER_USEC (1000L) +#endif +static __inline__unsigned long timespec_to_jiffies (struct timespec *value) {
@@ -46,16 +59,16 @@if (sec >= (MAX_JIFFY_OFFSET /HZ ))return MAX_JIFFY_OFFSET ; - nsec +=1000000000L /HZ -1 ; - nsec /=1000000000L /HZ ; + nsec +=NSEC_PER_SEC /HZ -1 ; + nsec /=NSEC_PER_SEC /HZ ;return HZ * sec + nsec; }static __inline__void -jiffies_to_timespec (unsigned long jiffies,struct timespec *value) +jiffies_to_timespec (unsigned long _jiffies,struct timespec *value) { - value->tv_nsec = (jiffies %HZ ) * (1000000000L /HZ ); - value->tv_sec = jiffies /HZ ; + value->tv_nsec = (_jiffies %HZ ) * (NSEC_PER_SEC /HZ ); + value->tv_sec = _jiffies /HZ ; }/* Same for "timeval" */
@@ -124,6 +137,7 @@#ifdef __KERNEL__extern void do_gettimeofday (struct timeval *tv);extern void do_settimeofday (struct timeval *tv); +extern int do_sys_settimeofday (struct timeval *tv,struct timezone *tz);#endif #define FD_SETSIZE __FD_SETSIZE
include/linux/timer.h +14 -1
@@ -14,15 +14,18 @@* timeouts. You can use this field to distinguish between the different * invocations. */ +struct timer_list {struct list_head list;unsigned long expires; +long sub_expires;unsigned long data;void (*function)(unsigned long ); };extern void add_timer (struct timer_list * timer);extern int del_timer (struct timer_list * timer); +extern void update_real_wall_time (void );#ifdef CONFIG_SMP extern int del_timer_sync (struct timer_list * timer);
@@ -37,14 +40,24 @@* If the timer is known to be not pending (ie, in the handler), mod_timer * is less efficient than a->expires = b; add_timer(a). */ +#ifdef CONFIG_HIGH_RES_TIMERS +int mod_timer_hr (struct timer_list *timer, +unsigned long expires, +long sub_expires); +#else +#define mod_timer_hr (a,b,c) mod_timer(a,b) +#endif +int mod_timer (struct timer_list *timer,unsigned long expires);extern void it_real_fn (unsigned long );static inline void init_timer (struct timer_list * timer) { - timer->list.next = timer->list.prev =NULL ; + timer->sub_expires =0 ; + timer->list.next = timer->list.prev =(struct list_head *)NULL ; } +#define TIMER_INIT (fun) {function: fun}static inline int timer_pending (const struct timer_list * timer) {
init/Config.help +10 -0
@@ -115,3 +115,13 @@ replacement for kerneld.) Say Y here and read about configuring it in <file:Documentation/kmod.txt>. +Configure timer list size +CONFIG_TIMERLIST_512 + This choice allows you to choose the timer list size you want. The + list insert time is Order(N/size) where N is the number of active + timers. Each list head is 8 bytes, thus a 512 list size requires 4K + bytes. Use larger numbers if you will be using a large number of + timers and are more concerned about list insertion time than the extra + memory usage. (The list size must be a power of 2.) + +
init/Config.in +21 -0
@@ -9,6 +9,27 @@ bool 'System V IPC' CONFIG_SYSVIPC bool 'BSD Process Accounting' CONFIG_BSD_PROCESS_ACCT bool 'Sysctl support' CONFIG_SYSCTL +choice 'Size of timer list?' \ + "512 CONFIG_TIMERLIST_512 \ + 1024 CONFIG_TIMERLIST_1k \ + 2048 CONFIG_TIMERLIST_2k \ + 4096 CONFIG_TIMERLIST_4k \ + 8192 CONFIG_TIMERLIST_8k" 512 +if [ "$CONFIG_TIMERLIST_512" = "y" ]; then + define_int CONFIG_NEW_TIMER_LISTSIZE 512 +fi +if [ "$CONFIG_TIMERLIST_1k" = "y" ]; then + define_int CONFIG_NEW_TIMER_LISTSIZE 1024 +fi +if [ "$CONFIG_TIMERLIST_2k" = "y" ]; then + define_int CONFIG_NEW_TIMER_LISTSIZE 2048 +fi +if [ "$CONFIG_TIMERLIST_4k" = "y" ]; then + define_int CONFIG_NEW_TIMER_LISTSIZE 4096 +fi +if [ "$CONFIG_TIMERLIST_8k" = "y" ]; then + define_int CONFIG_NEW_TIMER_LISTSIZE 8192 +fi endmenu mainmenu_option next_comment
kernel/ksyms.c +2 -0
@@ -55,6 +55,7 @@#include <linux/smp_lock.h> #include <linux/dnotify.h> #include <asm/checksum.h> +#include <linux/hrtime.h> #if defined(CONFIG_PROC_FS )#include <linux/proc_fs.h>
@@ -495,6 +496,7 @@EXPORT_SYMBOL (jiffies);EXPORT_SYMBOL (jiffies_64);EXPORT_SYMBOL (xtime); +EXPORT_SYMBOL (timer_conversion_bits);EXPORT_SYMBOL (do_gettimeofday);EXPORT_SYMBOL (do_settimeofday);#ifdef CONFIG_DEBUG_KERNEL
kernel/timer.c +291 -137
539 lines not on this page · raw message
net/ipv4/inetpeer.c +1 -1
@@ -98,7 +98,7 @@static void peer_check_expire (unsigned long dummy);static struct timer_list peer_periodic_timer = - { {NULL ,NULL },0 ,0 , &peer_check_expire }; +TIMER_INIT ( &peer_check_expire );/* Exported for sysctl_net_ipv4. */ int inet_peer_gc_mintime = 10 * HZ,
Quoted 3 lines · george anzinger
hash list. This change makes it easy to configure the list size for those who are concerned with performance. It also eliminates the "time out" for the cascade operation every
Could you make the list size configurable at boot time or by sysctl? It's almost impossible for distro vendors to get these kinds of tunables right for everyone, so making them dynamic is preferred.
-ben
Quoted 11 lines · Benjamin LaHaise
Quoted 3 lines · george anzinger
hash list. This change makes it easy to configure the list size for those who are concerned with performance. It also eliminates the "time out" for the cascade operation every
Could you make the list size configurable at boot time or by sysctl? It's almost impossible for distro vendors to get these kinds of tunables right for everyone, so making them dynamic is preferred.
-ben
Hm, that would require dynamic allocation of the memory, probably not an issue, but the masks would also need to be dynamic. The question is is it worth it. The 512 entry list seems to handle a very large number of timers with no trouble. We did tests measuring timer arm times with 4000 timers in the list. The slope was so low that we did not even try to increase the list size.
Signature · 5 lines
George Anzinger [email protected] High-res-timers: http://sourceforge.net/projects/high-res-timers/ Preemption patch: http://www.kernel.org/pub/linux/kernel/people/rml
George, your patch has 479 instances of eight-contiguous-blanks. Please use tabs.
I have great deals going on used editors at present ;)
Quoted 5 lines · Andrew Morton
George, your patch has 479 instances of eight-contiguous-blanks. Please use tabs.
I have great deals going on used editors at present ;)
Yea, I just need to find the right option to set in emacs. Been busy too chasing the 2.5 kernel train to take the time to find it.
A much bigger issue is that only two parts of the 4 seem to have made it to the list. Is there a size restriction some where?
Signature · 5 lines
George Anzinger [email protected] High-res-timers: http://sourceforge.net/projects/high-res-timers/ Preemption patch: http://www.kernel.org/pub/linux/kernel/people/rml
--On Thursday, September 26, 2002 20:07:05 -0700 george anzinger
Quoted 3 lines · <[email protected]> wrote:
A much bigger issue is that only two parts of the 4 seem to have made it to the list. Is there a size restriction some where?
Yes, lkml discards all mail over 100k. I spent a week awhile back discovering this the hard way.
Dave McCracken
======================================================================
Dave McCracken IBM Linux Base Kernel Team 1-512-838-3059
[email protected] T/L 678-3059
Quoted 11 lines · Dave McCracken
--On Thursday, September 26, 2002 20:07:05 -0700 george anzinger
Quoted 3 lines · <[email protected]> wrote:
A much bigger issue is that only two parts of the 4 seem to have made it to the list. Is there a size restriction some where?
Yes, lkml discards all mail over 100k. I spent a week awhile back discovering this the hard way.
Well that explains part 4, but part 3 is smaller than part 2 and it is lost. I have sent it several times... IT is checking.
Signature · 5 lines
George Anzinger [email protected] High-res-timers: http://sourceforge.net/projects/high-res-timers/ Preemption patch: http://www.kernel.org/pub/linux/kernel/people/rml
On Thu, Sep 26, 2002 at 08:07:05PM -0700, george anzinger wrote:
Andrew Morton wrote:
>
> George, your patch has 479 instances of eight-contiguous-blanks. > Please use tabs.
>
> I have great deals going on used editors at present ;)
Yea, I just need to find the right option to set in emacs. Been busy too chasing the 2.5 kernel train to take the time to find it.
(setq indent-tabs-mode t)
--cw