Commit d0551261 authored by Dmitrii Banshchikov's avatar Dmitrii Banshchikov Committed by Daniel Borkmann

bpf: Add bpf_ktime_get_coarse_ns helper

The helper uses CLOCK_MONOTONIC_COARSE source of time that is less
accurate but more performant.

We have a BPF CGROUP_SKB firewall that supports event logging through
bpf_perf_event_output(). Each event has a timestamp and currently we use
bpf_ktime_get_ns() for it. Use of bpf_ktime_get_coarse_ns() saves ~15-20
ns in time required for event logging.

bpf_ktime_get_ns():
EgressLogByRemoteEndpoint                              113.82ns    8.79M

bpf_ktime_get_coarse_ns():
EgressLogByRemoteEndpoint                               95.40ns   10.48M
Signed-off-by: default avatarDmitrii Banshchikov <me@ubique.spb.ru>
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
Acked-by: default avatarMartin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/20201117184549.257280-1-me@ubique.spb.ru
parent ea87ae85
......@@ -1842,6 +1842,7 @@ extern const struct bpf_func_proto bpf_copy_from_user_proto;
extern const struct bpf_func_proto bpf_snprintf_btf_proto;
extern const struct bpf_func_proto bpf_per_cpu_ptr_proto;
extern const struct bpf_func_proto bpf_this_cpu_ptr_proto;
extern const struct bpf_func_proto bpf_ktime_get_coarse_ns_proto;
const struct bpf_func_proto *bpf_tracing_func_proto(
enum bpf_func_id func_id, const struct bpf_prog *prog);
......
......@@ -3797,6 +3797,16 @@ union bpf_attr {
* is cleared if the flag is not specified.
* Return
* **-EINVAL** if invalid *flags* are passed, zero otherwise.
*
* u64 bpf_ktime_get_coarse_ns(void)
* Description
* Return a coarse-grained version of the time elapsed since
* system boot, in nanoseconds. Does not include time the system
* was suspended.
*
* See: **clock_gettime**\ (**CLOCK_MONOTONIC_COARSE**)
* Return
* Current *ktime*.
*/
#define __BPF_FUNC_MAPPER(FN) \
FN(unspec), \
......@@ -3959,6 +3969,7 @@ union bpf_attr {
FN(task_storage_delete), \
FN(get_current_task_btf), \
FN(bprm_opts_set), \
FN(ktime_get_coarse_ns), \
/* */
/* integer value in 'imm' field of BPF_CALL instruction selects which helper
......
......@@ -2211,6 +2211,7 @@ const struct bpf_func_proto bpf_get_smp_processor_id_proto __weak;
const struct bpf_func_proto bpf_get_numa_node_id_proto __weak;
const struct bpf_func_proto bpf_ktime_get_ns_proto __weak;
const struct bpf_func_proto bpf_ktime_get_boot_ns_proto __weak;
const struct bpf_func_proto bpf_ktime_get_coarse_ns_proto __weak;
const struct bpf_func_proto bpf_get_current_pid_tgid_proto __weak;
const struct bpf_func_proto bpf_get_current_uid_gid_proto __weak;
......
......@@ -167,6 +167,17 @@ const struct bpf_func_proto bpf_ktime_get_boot_ns_proto = {
.ret_type = RET_INTEGER,
};
BPF_CALL_0(bpf_ktime_get_coarse_ns)
{
return ktime_get_coarse_ns();
}
const struct bpf_func_proto bpf_ktime_get_coarse_ns_proto = {
.func = bpf_ktime_get_coarse_ns,
.gpl_only = false,
.ret_type = RET_INTEGER,
};
BPF_CALL_0(bpf_get_current_pid_tgid)
{
struct task_struct *task = current;
......@@ -685,6 +696,8 @@ bpf_base_func_proto(enum bpf_func_id func_id)
return &bpf_ktime_get_ns_proto;
case BPF_FUNC_ktime_get_boot_ns:
return &bpf_ktime_get_boot_ns_proto;
case BPF_FUNC_ktime_get_coarse_ns:
return &bpf_ktime_get_coarse_ns_proto;
case BPF_FUNC_ringbuf_output:
return &bpf_ringbuf_output_proto;
case BPF_FUNC_ringbuf_reserve:
......
......@@ -1280,6 +1280,8 @@ bpf_tracing_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
return &bpf_ktime_get_ns_proto;
case BPF_FUNC_ktime_get_boot_ns:
return &bpf_ktime_get_boot_ns_proto;
case BPF_FUNC_ktime_get_coarse_ns:
return &bpf_ktime_get_coarse_ns_proto;
case BPF_FUNC_tail_call:
return &bpf_tail_call_proto;
case BPF_FUNC_get_current_pid_tgid:
......
......@@ -3797,6 +3797,16 @@ union bpf_attr {
* is cleared if the flag is not specified.
* Return
* **-EINVAL** if invalid *flags* are passed, zero otherwise.
*
* u64 bpf_ktime_get_coarse_ns(void)
* Description
* Return a coarse-grained version of the time elapsed since
* system boot, in nanoseconds. Does not include time the system
* was suspended.
*
* See: **clock_gettime**\ (**CLOCK_MONOTONIC_COARSE**)
* Return
* Current *ktime*.
*/
#define __BPF_FUNC_MAPPER(FN) \
FN(unspec), \
......@@ -3959,6 +3969,7 @@ union bpf_attr {
FN(task_storage_delete), \
FN(get_current_task_btf), \
FN(bprm_opts_set), \
FN(ktime_get_coarse_ns), \
/* */
/* integer value in 'imm' field of BPF_CALL instruction selects which helper
......
Markdown is supported
0%
or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment