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net: set the minimum for net_hotdata.netdev_budget_usecs

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Commit 7acf8a1e8a ("Replace 2 jiffies with sysctl netdev_budget_usecs
to enable softirq tuning") added a possibility to set
net_hotdata.netdev_budget_usecs, but added no lower bound checking.

Commit a4837980fd ("net: revert default NAPI poll timeout to 2 jiffies")
made the *initial* value HZ-dependent, so the initial value is at least
2 jiffies even for lower HZ values (2 ms for 1000 Hz, 8ms for 250 Hz, 20
ms for 100 Hz).

But a user still can set improper values by a sysctl. Set .extra1
(the lower bound) for net_hotdata.netdev_budget_usecs to the same value
as in the latter commit. That is to 2 jiffies.

Fixes: a4837980fd ("net: revert default NAPI poll timeout to 2 jiffies")
Fixes: 7acf8a1e8a ("Replace 2 jiffies with sysctl netdev_budget_usecs to enable softirq tuning")
Signed-off-by: Jiri Slaby (SUSE) <jirislaby@kernel.org>
Cc: Dmitry Yakunin <zeil@yandex-team.ru>
Cc: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Link: https://patch.msgid.link/20250220110752.137639-1-jirislaby@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Jiri Slaby (SUSE) 2025-02-20 12:07:52 +01:00 • committed by Jakub Kicinski
parent 0e4427f8f5
commit c180188ec0
1 changed files with 2 additions and 1 deletions
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3
net/core/sysctl_net_core.c
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@ -34,6 +34,7 @@ static int min_sndbuf = SOCK_MIN_SNDBUF;
static int min_rcvbuf = SOCK_MIN_RCVBUF;
static int max_skb_frags = MAX_SKB_FRAGS;
static int min_mem_pcpu_rsv = SK_MEMORY_PCPU_RESERVE;
static int netdev_budget_usecs_min = 2 * USEC_PER_SEC / HZ;
static int net_msg_warn; /* Unused, but still a sysctl */
@ -587,7 +588,7 @@ static struct ctl_table net_core_table[] = {
.maxlen = sizeof(unsigned int),
.mode = 0644,
.proc_handler = proc_dointvec_minmax,
.extra1 = SYSCTL_ZERO,
.extra1 = &netdev_budget_usecs_min,
},
{
.procname = "fb_tunnels_only_for_init_net",