>>> On Mon, Feb 25, 2008 at 5:09 PM, in message
<20080225220950.GI2659@xxxxxxxxxx>, Pavel Machek <pavel@xxxxxx> wrote:
> Hi!
>
>> From: Peter W.Morreale <pmorreale@xxxxxxxxxx>
>>
>> This patch adds the adaptive spin lock busywait to rtmutexes. It adds
>> a new tunable: rtmutex_timeout, which is the companion to the
>> rtlock_timeout tunable.
>>
>> Signed-off-by: Peter W. Morreale <pmorreale@xxxxxxxxxx>
>
> Not signed off by you?
I wasn't sure if this was appropriate for me to do. This is the first time I was acting as "upstream" to someone. If that is what I am expected to do, consider this an "ack" for your remaining comments related to this.
>
>> diff --git a/kernel/Kconfig.preempt b/kernel/Kconfig.preempt
>> index ac1cbad..864bf14 100644
>> --- a/kernel/Kconfig.preempt
>> +++ b/kernel/Kconfig.preempt
>> @@ -214,6 +214,43 @@ config RTLOCK_DELAY
>> tunable at runtime via a sysctl. A setting of 0 (zero) disables
>> the adaptive algorithm entirely.
>>
>> +config ADAPTIVE_RTMUTEX
>> + bool "Adaptive real-time mutexes"
>> + default y
>> + depends on ADAPTIVE_RTLOCK
>> + help
>> + This option adds the adaptive rtlock spin/sleep algorithm to
>> + rtmutexes. In rtlocks, a significant gain in throughput
>> + can be seen by allowing rtlocks to spin for a distinct
>> + amount of time prior to going to sleep for deadlock avoidence.
>> +
>> + Typically, mutexes are used when a critical section may need to
>> + sleep due to a blocking operation. In the event the critical
>> + section does not need to sleep, an additional gain in throughput
>> + can be seen by avoiding the extra overhead of sleeping.
>
> Watch the whitespace. ... and do we need yet another config options?
>
>> +config RTMUTEX_DELAY
>> + int "Default delay (in loops) for adaptive mutexes"
>> + range 0 10000000
>> + depends on ADAPTIVE_RTMUTEX
>> + default "3000"
>> + help
>> + This allows you to specify the maximum delay a task will use
>> + to wait for a rt mutex before going to sleep. Note that that
>> + although the delay is implemented as a preemptable loop, tasks
>> + of like priority cannot preempt each other and this setting can
>> + result in increased latencies.
>> +
>> + The value is tunable at runtime via a sysctl. A setting of 0
>> + (zero) disables the adaptive algorithm entirely.
>
> Ouch.
? Is this reference to whitespace damage, or does the content need addressing?
>
>> +#ifdef CONFIG_ADAPTIVE_RTMUTEX
>> +
>> +#define mutex_adaptive_wait adaptive_wait
>> +#define mutex_prepare_adaptive_wait prepare_adaptive_wait
>> +
>> +extern int rtmutex_timeout;
>> +
>> +#define DECLARE_ADAPTIVE_MUTEX_WAITER(name) \
>> + struct adaptive_waiter name = { .owner = NULL, \
>> + .timeout = rtmutex_timeout, }
>> +
>> +#else
>> +
>> +#define DECLARE_ADAPTIVE_MUTEX_WAITER(name)
>> +
>> +#define mutex_adaptive_wait(lock, intr, waiter, busy) 1
>> +#define mutex_prepare_adaptive_wait(lock, busy) {}
>
> More evil macros. Macro does not behave like a function, make it
> inline function if you are replacing a function.
Ok
> Pavel
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