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use bpf global for netdev_max_backlog as ksym changes in 6.9 #88

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Merged
alan-maguire merged 1 commit into from
May 17, 2024
Merged

use bpf global for netdev_max_backlog as ksym changes in 6.9 #88

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11 changes: 4 additions & 7 deletions src/net_buffer_tuner.bpf.c
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Original file line number Diff line number Diff line change
Expand Up @@ -20,8 +20,6 @@
#include <bpftune/bpftune.bpf.h>
#include "net_buffer_tuner.h"

extern const void netdev_max_backlog __ksym;

#ifndef NET_RX_DROP
#define NET_RX_DROP 1
#endif
Expand All @@ -31,6 +29,8 @@ __u64 drop_interval_start = 0;

__u64 flow_limit_cpu_bitmap = 0;

int netdev_max_backlog = 0;

#ifdef BPFTUNE_LEGACY
SEC("kretprobe/enqueue_to_backlog")
int BPF_KRETPROBE(bpftune_enqueue_to_backlog, int ret)
Expand All @@ -40,9 +40,9 @@ int BPF_PROG(bpftune_enqueue_to_backlog, struct sk_buff *skb, int cpu,
unsigned int *qtail, int ret)
#endif
{
int max_backlog = netdev_max_backlog;
struct bpftune_event event = { 0 };
long old[3], new[3];
int max_backlog, *max_backlogp = (int *)&netdev_max_backlog;
__u64 time, cpubit;

/* a high-frequency event so bail early if we can... */
Expand All @@ -54,10 +54,7 @@ int BPF_PROG(bpftune_enqueue_to_backlog, struct sk_buff *skb, int cpu,
/* only sample subset of drops to reduce overhead. */
if ((drop_count % 4) != 0)
return 0;
if (bpf_probe_read_kernel(&max_backlog, sizeof(max_backlog),
max_backlogp))
return 0;


/* if we drop more than 1/16 of the backlog queue size/min,
* increase backlog queue size. This means as the queue size
* increases, the likliehood of hitting that limit decreases.
Expand Down
8 changes: 7 additions & 1 deletion src/net_buffer_tuner.c
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Original file line number Diff line number Diff line change
Expand Up @@ -29,10 +29,11 @@ static struct bpftunable_scenario scenarios[] = {
int init(struct bpftuner *tuner)
{
long cpu_bitmap = 0;
long max_backlog = 0;
int err;

bpftune_sysctl_read(0, "net.core.flow_limit_cpu_bitmap", &cpu_bitmap);

bpftune_sysctl_read(0, "net.core.netdev_max_backlog", &max_backlog);
err = bpftuner_bpf_open(net_buffer, tuner);
if (err)
return err;
Expand All @@ -41,6 +42,8 @@ int init(struct bpftuner *tuner)
return err;
bpftuner_bpf_var_set(net_buffer, tuner, flow_limit_cpu_bitmap,
cpu_bitmap);
bpftuner_bpf_var_set(net_buffer, tuner, netdev_max_backlog,
max_backlog);
err = bpftuner_bpf_attach(net_buffer, tuner);
if (err)
return err;
Expand Down Expand Up @@ -82,6 +85,9 @@ void event_handler(struct bpftuner *tuner,
tunable,
event->update[0].old[0],
event->update[0].new[0]);
/* update value of netdev_max_backlog for BPF program */
bpftuner_bpf_var_set(net_buffer, tuner, netdev_max_backlog,
event->update[0].new[0]);
break;
case FLOW_LIMIT_CPU_BITMAP:
bpftuner_tunable_sysctl_write(tuner, id, scenario,
Expand Down