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    SubjectRe: [PATCH] pm_qos: Add system bus performance parameter
    On Thu, Aug 26, 2010 at 09:13:23PM -0700, Saravana Kannan wrote:
    > Some drivers/devices might need some minimum system bus performance to
    > provide acceptable service. Provide a PM QoS parameter to send these requests
    > to.
    >
    > The new parameter is named "system bus performance" since it is generic enough
    > for the unit of the request to be frequency, bandwidth or something else that
    > might be appropriate. It's up to each implementation of the QoS provider to
    > define what the unit of the request would be.
    >
    > Signed-off-by: Saravana Kannan <skannan@codeaurora.org>
    > ---
    > kernel/pm_qos_params.c | 9 +++++++++
    > 1 files changed, 9 insertions(+), 0 deletions(-)
    >
    > diff --git a/kernel/pm_qos_params.c b/kernel/pm_qos_params.c
    > index 996a4de..1a44a67 100644
    > --- a/kernel/pm_qos_params.c
    > +++ b/kernel/pm_qos_params.c
    > @@ -93,12 +93,21 @@ static struct pm_qos_object network_throughput_pm_qos = {
    > .type = PM_QOS_MAX,
    > };
    >
    > +static BLOCKING_NOTIFIER_HEAD(system_bus_performance_notifier);
    > +static struct pm_qos_object system_bus_performance_pm_qos = {
    > + .requests = PLIST_HEAD_INIT(system_bus_performance_pm_qos.requests, pm_qos_lock),
    > + .notifiers = &system_bus_performance_notifier,
    > + .name = "system_bus_performance",
    > + .default_value = 0,
    > + .type = PM_QOS_MAX,
    > +};
    >
    > static struct pm_qos_object *pm_qos_array[] = {
    > &null_pm_qos,
    > &cpu_dma_pm_qos,
    > &network_lat_pm_qos,
    > &network_throughput_pm_qos
    > + &system_bus_performance_pm_qos
    > };
    >
    > static ssize_t pm_qos_power_write(struct file *filp, const char __user *buf,
    > --
    > 1.7.1.1
    > ---

    nack.

    Change the name to system_bus_throughput_pm_qos assuming KBS units and
    I'll ok it. It needs to be portable and without units I think drivers
    will start using magic numbers that will break when you go from a
    devices with 16 to 32 bus with the same clock.

    We had an email thread about this last year
    http://lkml.org/lkml/2009/12/31/143
    I don't recall solution ever coming out of it. I think you guys didn't
    like the idea of using units. Further I did post a patch adding
    something like using units. Although I looks like I botch the post the
    linux-pm as I can't seem to find it in the linux-pm archives :(
    http://lkml.org/lkml/2010/4/22/213

    Would you be ok with using throughput instead of a unit less performance
    magic number?


    --mark




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