On 15 January 2016 at 13:43, Prashanth Prakash <pprakash@xxxxxxxxxxxxxx> wrote: > cpc_read and cpc_write are used while holding the pcc_lock spin_lock, > so they need to be as fast as possible. acpi_os_read/write_memory > APIs linearly search through a list for cached mapping which is > quite expensive. Since the PCC subspace is already mapped into > virtual address space during initialization, we can just add the > offset and access the necessary CPPC registers. > > This patch + similar changes to PCC driver reduce the time per freq. > transition from around 200us to about 20us for cppc cpufreq driver > > Signed-off-by: Prashanth Prakash <pprakash@xxxxxxxxxxxxxx> > --- > drivers/acpi/cppc_acpi.c | 80 ++++++++++++++++++++++++++++++++++++++---------- > 1 file changed, 64 insertions(+), 16 deletions(-) Acked-by: Ashwin Chaugule <ashwin.chaugule@xxxxxxxxxx> -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
