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    Subject[PATCH] limit CPU time spent in kipmid (version 4)
    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: martin.wilck@ts.fujitsu.com
    Internet: http://ts.fujitsu.com
    Company Details: http://de.ts.fujitsu.com/imprint.html
    Signed-off-by: martin.wilck@ts.fujitsu.com
    --- 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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      Last update: 2009-06-04 20:53    [from the cache]
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