Hi all,I am sorry for the long silence. I am sending here a new version of my patch which takes into account Bela's suggestions (well, most of them). I compiled and tested it with 2.6.29.4, the results are similar as before. By setting kipmid_max_busy_us to a value between 100 and 500, it is possible to bring down kipmid CPU load to practically 0 without loosing too much ipmi throughput performance.
Please give me some feedback whether this patch will get merged, and if not, what improvement is needed.
Regards Martin -- Dr. Martin Wilck PRIMERGY System Software Engineer x86 Server Engineering Fujitsu Technology Solutions GmbH Heinz-Nixdorf-Ring 1 33106 Paderborn, Germany Phone: ++49 5251 525 2796 Fax: ++49 5251 525 2820 Email: [email protected] Internet: http://ts.fujitsu.com Company Details: http://de.ts.fujitsu.com/imprint.html
Signed-off-by: [email protected] --- linux-2.6.29.4/drivers/char/ipmi/ipmi_si_intf.c 2009-05-19 01:52:34.000000000 +0200 +++ linux-2.6.29-rc8/drivers/char/ipmi/ipmi_si_intf.c 2009-06-04 15:30:34.855398091 +0200 @@ -297,6 +297,9 @@ static int force_kipmid[SI_MAX_PARMS]; static int num_force_kipmid; +static unsigned int kipmid_max_busy_us[SI_MAX_PARMS]; +static int num_max_busy_us; + static int unload_when_empty = 1; static int try_smi_init(struct smi_info *smi); @@ -927,23 +930,56 @@ } } +#define ipmi_si_set_not_busy(timespec) \ + do { (timespec)->tv_nsec = -1; } while (0) +#define ipmi_si_is_busy(timespec) ((timespec)->tv_nsec != -1) + +static int ipmi_thread_busy_wait(enum si_sm_result smi_result, + const struct smi_info *smi_info, + struct timespec *busy_until) +{ + unsigned int max_busy_us = 0; + + if (smi_info->intf_num < num_max_busy_us) + max_busy_us = kipmid_max_busy_us[smi_info->intf_num]; + if (max_busy_us == 0 || smi_result != SI_SM_CALL_WITH_DELAY) + ipmi_si_set_not_busy(busy_until); + else if (!ipmi_si_is_busy(busy_until)) { + getnstimeofday(busy_until); + timespec_add_ns(busy_until, max_busy_us*NSEC_PER_USEC); + } else { + struct timespec now; + getnstimeofday(&now); + if (unlikely(timespec_compare(&now, busy_until) > 0)) { + ipmi_si_set_not_busy(busy_until); + return 0; + } + } + return 1; +} + static int ipmi_thread(void *data) { struct smi_info *smi_info = data; unsigned long flags; enum si_sm_result smi_result; + struct timespec busy_until; + ipmi_si_set_not_busy(&busy_until); set_user_nice(current, 19); while (!kthread_should_stop()) { + int busy_wait; spin_lock_irqsave(&(smi_info->si_lock), flags); smi_result = smi_event_handler(smi_info, 0); spin_unlock_irqrestore(&(smi_info->si_lock), flags); + busy_wait = ipmi_thread_busy_wait(smi_result, smi_info, + &busy_until); if (smi_result == SI_SM_CALL_WITHOUT_DELAY) ; /* do nothing */ - else if (smi_result == SI_SM_CALL_WITH_DELAY) + else if (smi_result == SI_SM_CALL_WITH_DELAY && busy_wait) schedule(); else - schedule_timeout_interruptible(1); + schedule_timeout_interruptible(0); } return 0; } @@ -1213,6 +1249,11 @@ MODULE_PARM_DESC(unload_when_empty, "Unload the module if no interfaces are" " specified or found, default is 1. Setting to 0" " is useful for hot add of devices using hotmod."); +module_param_array(kipmid_max_busy_us, uint, &num_max_busy_us, 0644); +MODULE_PARM_DESC(kipmid_max_busy_us, + "Max time (in microseconds) to busy-wait for IPMI data before" + " sleeping. 0 (default) means to wait forever. Set to 100-500" + " if kipmid is using up a lot of CPU time."); static void std_irq_cleanup(struct smi_info *info)
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