On Sat, Dec 18, 2021 at 2:16 PM Michał Mirosław wrote:
>
> On Sat, Dec 18, 2021 at 01:19:57PM -0800, Yury Norov wrote:
> > Don't call bitmap_weight() if the following code can get by
> > without it.
> >
> > Signed-off-by: Yury Norov
> > ---
> > drivers/net/dsa/b53/b53_common.c | 6 +---
cpumask and nodemask APIs are thin wrappers around basic bitmap API, and
corresponding files are not formally maintained. This patch adds them to
BITMAP_API section, so that bitmap folks would have closer look at it.
Signed-off-by: Yury Norov
---
MAINTAINERS | 4
1 file changed, 4 insertion
Pull bitmap_weight_{cmp,eq,gt,ge,lt,le} from mother kernel and
use where applicable.
Signed-off-by: Yury Norov
---
tools/include/linux/bitmap.h | 44
tools/lib/bitmap.c | 20
tools/perf/util/pmu.c| 2 +-
3 files changed, 65
Similarly to the online cpus, the cpu_active_mask is actively used
in the kernel. This patch adds a counter for active cpus, so that
users that call num_active_cpus() would know the result immediately,
instead of calling the bitmap_weight for the mask.
Suggested-by: Nicholas Piggin
Signed-off-by:
Similarly to the online cpus, the cpu_present_mask is actively used
in the kernel. This patch adds a counter for present cpus, so that
users that call num_present_cpus() would know the result immediately,
instead of calling the bitmap_weight for the mask.
Suggested-by: Nicholas Piggin
Signed-off-
Similarly to the online cpus, the cpu_possible_mask is actively used
in the kernel. This patch adds a counter for possible cpus, so that
users that call num_possible_cpus() would know the result immediately,
instead of calling the bitmap_weight for the mask underlying.
Suggested-by: Nicholas Piggi
cpu_online_mask has an associate counter of online cpus, which should be
initialized in init_cpu_online()
Fixes: 0c09ab96fc82010 (cpu/hotplug: Cache number of online CPUs)
Signed-off-by: Yury Norov
---
kernel/cpu.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/kernel/cpu.c b/kernel/cpu.c
i
Kernel code calls num_node_state() to compare number of nodes with a given
number. The underlying code calls bitmap_weight(), and we can do it more
efficiently with num_node_state_eq because conditional nodes_weight may
stop traversing the nodemask earlier, as soon as condition is met.
Signed-off-
Kernel code calls nodes_weight() to compare the weight of nodemask with
a given number. We can do it more efficiently with nodes_weight_{eq, ...}
because conditional nodes_weight may stop traversing the nodemask earlier,
as soon as condition is met.
Signed-off-by: Yury Norov
---
drivers/acpi/num
Kernel code calls cpumask_weight() to compare the weight of cpumask with
a given number. We can do it more efficiently with cpumask_weight_{eq, ...}
because conditional cpumask_weight may stop traversing the cpumask earlier,
as soon as condition is met.
Signed-off-by: Yury Norov
---
arch/ia64/mm
Kernel code calls bitmap_weight() to compare the weight of bitmap with
a given number. We can do it more efficiently with bitmap_weight_{eq, ...}
because conditional bitmap_weight may stop traversing the bitmap earlier,
as soon as condition is met.
This patch replaces bitmap_weight with conditiona
Many kernel users use bitmap_weight() to compare the result against
some number or expression:
if (bitmap_weight(...) > 1)
do_something();
It works OK, but may be significantly improved for large bitmaps: if
first few words count set bits to a number greater than given, we
Kernel code calls nodes_weight() to check if any bit of a given nodemask is
set. We can do it more efficiently with nodes_empty() because nodes_empty()
stops traversing the nodemask as soon as it finds first set bit, while
nodes_weight() counts all bits unconditionally.
Signed-off-by: Yury Norov
In many cases, kernel code calls cpumask_weight() to check if any bit of
a given cpumask is set. We can do it more efficiently with cpumask_empty()
because cpumask_empty() stops traversing the cpumask as soon as it finds
first set bit, while cpumask_weight() counts all bits unconditionally.
Signed
In many cases, kernel code calls bitmap_weight() to check if any bit of
a given bitmap is set. It's better to use bitmap_empty() in that case
because bitmap_empty() stops traversing the bitmap as soon as it finds
first set bit, while bitmap_weight() counts all bits unconditionally.
Signed-off-by:
Mellanox driver has an open-coded for_each_set_bit(). Fix it.
Signed-off-by: Yury Norov
---
drivers/net/ethernet/mellanox/mlx4/cmd.c | 23 ++-
1 file changed, 6 insertions(+), 17 deletions(-)
diff --git a/drivers/net/ethernet/mellanox/mlx4/cmd.c
b/drivers/net/ethernet/mella
Some drivers declare num_active_cpus and num_present_cpus,
despite that kernel has macros with corresponding names in
linux/cpumask.h, and the drivers include cpumask.h
The following patches switch num_*_cpus() to real functions,
which causes build failures for the drivers.
Signed-off-by: Yury No
Don't call bitmap_weight() if the following code can get by
without it.
Signed-off-by: Yury Norov
---
drivers/net/dsa/b53/b53_common.c | 6 +-
drivers/net/ethernet/broadcom/bcmsysport.c | 6 +-
drivers/thermal/intel/intel_powerclamp.c | 9 +++--
3 files changed, 5 inserti
In many cases people use bitmap_weight()-based functions to compare
the result against a number of expression:
if (cpumask_weight(...) > 1)
do_something();
This may take considerable amount of time on many-cpus machines because
cpumask_weight(...) will traverse every word
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