On Sun, 14 Nov 2021 17:16:05 +0100 Christophe JAILLET <christophe.jaillet@xxxxxxxxxx> wrote: > 'MAX_RT_PRIO' is 100. Instead of clearing bits in 'array->bitmap' one at a > time, use 'bitmap_clear()' which will do the same but much faster I don't see this being an improvement as long as we need to keep the loop to do the initialization of the list head. > > Signed-off-by: Christophe JAILLET <christophe.jaillet@xxxxxxxxxx> > --- > Not sure that this patch is really of any use, but it is the occasion for > me to spot that there seems to be an off by one in the rt scheduler. > > 'array->bitmap' is MAX_RT_PRIO+1 long. (see [1]) > The last bit seems to be reserved as a sentinel. > > Shouldn't this sentinel, in the code above, be set as: > __set_bit(MAX_RT_PRIO + 1, array->bitmap); No. The first bit is zero. The last bit in the bitmask is MAX_RT_PRIO. The bitmask has MAX_RT_PRIO + 1 bits. Your __set_bit() above would be an off by one error in overwriting the size of the bitmask. -- Steve
