* [PATCH bpf-next v2 1/2] bpf: Add ability to pin bpf timer to calling CPU
2023-10-04 16:23 [PATCH bpf-next v2 0/2] bpf: Add ability to pin bpf timer to calling CPU David Vernet
@ 2023-10-04 16:23 ` David Vernet
2023-10-08 4:09 ` Hou Tao
2023-10-04 16:23 ` [PATCH bpf-next v2 2/2] bpf/selftests: Test pinning bpf timer to a core David Vernet
2023-10-09 14:40 ` [PATCH bpf-next v2 0/2] bpf: Add ability to pin bpf timer to calling CPU patchwork-bot+netdevbpf
2 siblings, 1 reply; 6+ messages in thread
From: David Vernet @ 2023-10-04 16:23 UTC (permalink / raw)
To: bpf
Cc: ast, daniel, andrii, martin.lau, song, yonghong.song,
john.fastabend, kpsingh, sdf, haoluo, jolsa, linux-kernel,
kernel-team
BPF supports creating high resolution timers using bpf_timer_* helper
functions. Currently, only the BPF_F_TIMER_ABS flag is supported, which
specifies that the timeout should be interpreted as absolute time. It
would also be useful to be able to pin that timer to a core. For
example, if you wanted to make a subset of cores run without timer
interrupts, and only have the timer be invoked on a single core.
This patch adds support for this with a new BPF_F_TIMER_CPU_PIN flag.
When specified, the HRTIMER_MODE_PINNED flag is passed to
hrtimer_start(). A subsequent patch will update selftests to validate.
Acked-by: Song Liu <song@kernel.org>
Signed-off-by: David Vernet <void@manifault.com>
---
include/uapi/linux/bpf.h | 4 ++++
kernel/bpf/helpers.c | 5 ++++-
tools/include/uapi/linux/bpf.h | 4 ++++
3 files changed, 12 insertions(+), 1 deletion(-)
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 70bfa997e896..a7d4a1a69f21 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -5096,6 +5096,8 @@ union bpf_attr {
* **BPF_F_TIMER_ABS**
* Start the timer in absolute expire value instead of the
* default relative one.
+ * **BPF_F_TIMER_CPU_PIN**
+ * Timer will be pinned to the CPU of the caller.
*
* Return
* 0 on success.
@@ -7309,9 +7311,11 @@ struct bpf_core_relo {
* Flags to control bpf_timer_start() behaviour.
* - BPF_F_TIMER_ABS: Timeout passed is absolute time, by default it is
* relative to current time.
+ * - BPF_F_TIMER_CPU_PIN: Timer will be pinned to the CPU of the caller.
*/
enum {
BPF_F_TIMER_ABS = (1ULL << 0),
+ BPF_F_TIMER_CPU_PIN = (1ULL << 1),
};
/* BPF numbers iterator state */
diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c
index dd1c69ee3375..d2840dd5b00d 100644
--- a/kernel/bpf/helpers.c
+++ b/kernel/bpf/helpers.c
@@ -1272,7 +1272,7 @@ BPF_CALL_3(bpf_timer_start, struct bpf_timer_kern *, timer, u64, nsecs, u64, fla
if (in_nmi())
return -EOPNOTSUPP;
- if (flags > BPF_F_TIMER_ABS)
+ if (flags & ~(BPF_F_TIMER_ABS | BPF_F_TIMER_CPU_PIN))
return -EINVAL;
__bpf_spin_lock_irqsave(&timer->lock);
t = timer->timer;
@@ -1286,6 +1286,9 @@ BPF_CALL_3(bpf_timer_start, struct bpf_timer_kern *, timer, u64, nsecs, u64, fla
else
mode = HRTIMER_MODE_REL_SOFT;
+ if (flags & BPF_F_TIMER_CPU_PIN)
+ mode |= HRTIMER_MODE_PINNED;
+
hrtimer_start(&t->timer, ns_to_ktime(nsecs), mode);
out:
__bpf_spin_unlock_irqrestore(&timer->lock);
diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index 70bfa997e896..a7d4a1a69f21 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -5096,6 +5096,8 @@ union bpf_attr {
* **BPF_F_TIMER_ABS**
* Start the timer in absolute expire value instead of the
* default relative one.
+ * **BPF_F_TIMER_CPU_PIN**
+ * Timer will be pinned to the CPU of the caller.
*
* Return
* 0 on success.
@@ -7309,9 +7311,11 @@ struct bpf_core_relo {
* Flags to control bpf_timer_start() behaviour.
* - BPF_F_TIMER_ABS: Timeout passed is absolute time, by default it is
* relative to current time.
+ * - BPF_F_TIMER_CPU_PIN: Timer will be pinned to the CPU of the caller.
*/
enum {
BPF_F_TIMER_ABS = (1ULL << 0),
+ BPF_F_TIMER_CPU_PIN = (1ULL << 1),
};
/* BPF numbers iterator state */
--
2.41.0
^ permalink raw reply related [flat|nested] 6+ messages in thread* Re: [PATCH bpf-next v2 1/2] bpf: Add ability to pin bpf timer to calling CPU
2023-10-04 16:23 ` [PATCH bpf-next v2 1/2] " David Vernet
@ 2023-10-08 4:09 ` Hou Tao
0 siblings, 0 replies; 6+ messages in thread
From: Hou Tao @ 2023-10-08 4:09 UTC (permalink / raw)
To: David Vernet, bpf
Cc: ast, daniel, andrii, martin.lau, song, yonghong.song,
john.fastabend, kpsingh, sdf, haoluo, jolsa, linux-kernel,
kernel-team
On 10/5/2023 12:23 AM, David Vernet wrote:
> BPF supports creating high resolution timers using bpf_timer_* helper
> functions. Currently, only the BPF_F_TIMER_ABS flag is supported, which
> specifies that the timeout should be interpreted as absolute time. It
> would also be useful to be able to pin that timer to a core. For
> example, if you wanted to make a subset of cores run without timer
> interrupts, and only have the timer be invoked on a single core.
>
> This patch adds support for this with a new BPF_F_TIMER_CPU_PIN flag.
> When specified, the HRTIMER_MODE_PINNED flag is passed to
> hrtimer_start(). A subsequent patch will update selftests to validate.
>
> Acked-by: Song Liu <song@kernel.org>
> Signed-off-by: David Vernet <void@manifault.com>
Acked-by: Hou Tao <houtao1@huawei.com>
^ permalink raw reply [flat|nested] 6+ messages in thread
* [PATCH bpf-next v2 2/2] bpf/selftests: Test pinning bpf timer to a core
2023-10-04 16:23 [PATCH bpf-next v2 0/2] bpf: Add ability to pin bpf timer to calling CPU David Vernet
2023-10-04 16:23 ` [PATCH bpf-next v2 1/2] " David Vernet
@ 2023-10-04 16:23 ` David Vernet
2023-10-08 4:23 ` Hou Tao
2023-10-09 14:40 ` [PATCH bpf-next v2 0/2] bpf: Add ability to pin bpf timer to calling CPU patchwork-bot+netdevbpf
2 siblings, 1 reply; 6+ messages in thread
From: David Vernet @ 2023-10-04 16:23 UTC (permalink / raw)
To: bpf
Cc: ast, daniel, andrii, martin.lau, song, yonghong.song,
john.fastabend, kpsingh, sdf, haoluo, jolsa, linux-kernel,
kernel-team
Now that we support pinning a BPF timer to the current core, we should
test it with some selftests. This patch adds two new testcases to the
timer suite, which verifies that a BPF timer both with and without
BPF_F_TIMER_ABS, can be pinned to the calling core with
BPF_F_TIMER_CPU_PIN.
Acked-by: Song Liu <song@kernel.org>
Signed-off-by: David Vernet <void@manifault.com>
---
.../testing/selftests/bpf/prog_tests/timer.c | 4 ++
tools/testing/selftests/bpf/progs/timer.c | 63 ++++++++++++++++++-
2 files changed, 66 insertions(+), 1 deletion(-)
diff --git a/tools/testing/selftests/bpf/prog_tests/timer.c b/tools/testing/selftests/bpf/prog_tests/timer.c
index 290c21dbe65a..d8bc838445ec 100644
--- a/tools/testing/selftests/bpf/prog_tests/timer.c
+++ b/tools/testing/selftests/bpf/prog_tests/timer.c
@@ -14,6 +14,7 @@ static int timer(struct timer *timer_skel)
ASSERT_EQ(timer_skel->data->callback_check, 52, "callback_check1");
ASSERT_EQ(timer_skel->data->callback2_check, 52, "callback2_check1");
+ ASSERT_EQ(timer_skel->bss->pinned_callback_check, 0, "pinned_callback_check1");
prog_fd = bpf_program__fd(timer_skel->progs.test1);
err = bpf_prog_test_run_opts(prog_fd, &topts);
@@ -32,6 +33,9 @@ static int timer(struct timer *timer_skel)
/* check that timer_cb3() was executed twice */
ASSERT_EQ(timer_skel->bss->abs_data, 12, "abs_data");
+ /* check that timer_cb_pinned() was executed twice */
+ ASSERT_EQ(timer_skel->bss->pinned_callback_check, 2, "pinned_callback_check");
+
/* check that there were no errors in timer execution */
ASSERT_EQ(timer_skel->bss->err, 0, "err");
diff --git a/tools/testing/selftests/bpf/progs/timer.c b/tools/testing/selftests/bpf/progs/timer.c
index 9a16d95213e1..8b946c8188c6 100644
--- a/tools/testing/selftests/bpf/progs/timer.c
+++ b/tools/testing/selftests/bpf/progs/timer.c
@@ -51,7 +51,7 @@ struct {
__uint(max_entries, 1);
__type(key, int);
__type(value, struct elem);
-} abs_timer SEC(".maps");
+} abs_timer SEC(".maps"), soft_timer_pinned SEC(".maps"), abs_timer_pinned SEC(".maps");
__u64 bss_data;
__u64 abs_data;
@@ -59,6 +59,8 @@ __u64 err;
__u64 ok;
__u64 callback_check = 52;
__u64 callback2_check = 52;
+__u64 pinned_callback_check;
+__s32 pinned_cpu;
#define ARRAY 1
#define HTAB 2
@@ -329,3 +331,62 @@ int BPF_PROG2(test3, int, a)
return 0;
}
+
+/* callback for pinned timer */
+static int timer_cb_pinned(void *map, int *key, struct bpf_timer *timer)
+{
+ __s32 cpu = bpf_get_smp_processor_id();
+
+ if (cpu != pinned_cpu)
+ err |= 16384;
+
+ pinned_callback_check++;
+ return 0;
+}
+
+static void test_pinned_timer(bool soft)
+{
+ int key = 0;
+ void *map;
+ struct bpf_timer *timer;
+ __u64 flags = BPF_F_TIMER_CPU_PIN;
+ __u64 start_time;
+
+ if (soft) {
+ map = &soft_timer_pinned;
+ start_time = 0;
+ } else {
+ map = &abs_timer_pinned;
+ start_time = bpf_ktime_get_boot_ns();
+ flags |= BPF_F_TIMER_ABS;
+ }
+
+ timer = bpf_map_lookup_elem(map, &key);
+ if (timer) {
+ if (bpf_timer_init(timer, map, CLOCK_BOOTTIME) != 0)
+ err |= 4096;
+ bpf_timer_set_callback(timer, timer_cb_pinned);
+ pinned_cpu = bpf_get_smp_processor_id();
+ bpf_timer_start(timer, start_time + 1000, flags);
+ } else {
+ err |= 8192;
+ }
+}
+
+SEC("fentry/bpf_fentry_test4")
+int BPF_PROG2(test4, int, a)
+{
+ bpf_printk("test4");
+ test_pinned_timer(true);
+
+ return 0;
+}
+
+SEC("fentry/bpf_fentry_test5")
+int BPF_PROG2(test5, int, a)
+{
+ bpf_printk("test5");
+ test_pinned_timer(false);
+
+ return 0;
+}
--
2.41.0
^ permalink raw reply related [flat|nested] 6+ messages in thread* Re: [PATCH bpf-next v2 2/2] bpf/selftests: Test pinning bpf timer to a core
2023-10-04 16:23 ` [PATCH bpf-next v2 2/2] bpf/selftests: Test pinning bpf timer to a core David Vernet
@ 2023-10-08 4:23 ` Hou Tao
0 siblings, 0 replies; 6+ messages in thread
From: Hou Tao @ 2023-10-08 4:23 UTC (permalink / raw)
To: David Vernet, bpf
Cc: ast, daniel, andrii, martin.lau, song, yonghong.song,
john.fastabend, kpsingh, sdf, haoluo, jolsa, linux-kernel,
kernel-team
On 10/5/2023 12:23 AM, David Vernet wrote:
> Now that we support pinning a BPF timer to the current core, we should
> test it with some selftests. This patch adds two new testcases to the
> timer suite, which verifies that a BPF timer both with and without
> BPF_F_TIMER_ABS, can be pinned to the calling core with
> BPF_F_TIMER_CPU_PIN.
>
> Acked-by: Song Liu <song@kernel.org>
> Signed-off-by: David Vernet <void@manifault.com>
Acked-by: Hou Tao <houtao1@huawei.com>
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH bpf-next v2 0/2] bpf: Add ability to pin bpf timer to calling CPU
2023-10-04 16:23 [PATCH bpf-next v2 0/2] bpf: Add ability to pin bpf timer to calling CPU David Vernet
2023-10-04 16:23 ` [PATCH bpf-next v2 1/2] " David Vernet
2023-10-04 16:23 ` [PATCH bpf-next v2 2/2] bpf/selftests: Test pinning bpf timer to a core David Vernet
@ 2023-10-09 14:40 ` patchwork-bot+netdevbpf
2 siblings, 0 replies; 6+ messages in thread
From: patchwork-bot+netdevbpf @ 2023-10-09 14:40 UTC (permalink / raw)
To: David Vernet
Cc: bpf, ast, daniel, andrii, martin.lau, song, yonghong.song,
john.fastabend, kpsingh, sdf, haoluo, jolsa, linux-kernel,
kernel-team
Hello:
This series was applied to bpf/bpf-next.git (master)
by Daniel Borkmann <daniel@iogearbox.net>:
On Wed, 4 Oct 2023 11:23:37 -0500 you wrote:
> BPF supports creating high resolution timers using bpf_timer_* helper
> functions. Currently, only the BPF_F_TIMER_ABS flag is supported, which
> specifies that the timeout should be interpreted as absolute time. It
> would also be useful to be able to pin that timer to a core. For
> example, if you wanted to make a subset of cores run without timer
> interrupts, and only have the timer be invoked on a single core.
>
> [...]
Here is the summary with links:
- [bpf-next,v2,1/2] bpf: Add ability to pin bpf timer to calling CPU
https://git.kernel.org/bpf/bpf-next/c/d6247ecb6c1e
- [bpf-next,v2,2/2] bpf/selftests: Test pinning bpf timer to a core
https://git.kernel.org/bpf/bpf-next/c/0d7ae0686075
You are awesome, thank you!
--
Deet-doot-dot, I am a bot.
https://korg.docs.kernel.org/patchwork/pwbot.html
^ permalink raw reply [flat|nested] 6+ messages in thread