.../admin-guide/kernel-parameters.txt | 4 ++++ Documentation/admin-guide/nfs/nfsroot.rst | 3 +++ net/ipv4/ipconfig.c | 23 ++++++++++++++++--- 3 files changed, 27 insertions(+), 3 deletions(-)
During IP auto configuration, some drivers apparently need to wait a
certain length of time to settle; as this is not true for all drivers,
make this length of time configurable.
Signed-off-by: David Ventura <david@davidv.dev>
---
.../admin-guide/kernel-parameters.txt | 4 ++++
Documentation/admin-guide/nfs/nfsroot.rst | 3 +++
net/ipv4/ipconfig.c | 23 ++++++++++++++++---
3 files changed, 27 insertions(+), 3 deletions(-)
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index b47940577c10..b07a035642fa 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -2291,6 +2291,10 @@
ip= [IP_PNP]
See Documentation/admin-guide/nfs/nfsroot.rst.
+ ip.dev_wait_ms=
+ [IP_PNP]
+ See Documentation/admin-guide/nfs/nfsroot.rst.
+
ipcmni_extend [KNL,EARLY] Extend the maximum number of unique System V
IPC identifiers from 32,768 to 16,777,216.
diff --git a/Documentation/admin-guide/nfs/nfsroot.rst b/Documentation/admin-guide/nfs/nfsroot.rst
index 135218f33394..f26f7a342af6 100644
--- a/Documentation/admin-guide/nfs/nfsroot.rst
+++ b/Documentation/admin-guide/nfs/nfsroot.rst
@@ -223,6 +223,9 @@ ip=<client-ip>:<server-ip>:<gw-ip>:<netmask>:<hostname>:<device>:<autoconf>:<dns
/proc/net/ipconfig/ntp_servers to an NTP client before mounting the real
root filesystem if it is on NFS).
+ip.dev_wait_ms=<value>
+ Set the number of milliseconds to delay after opening the network device
+ which will be autoconfigured. Defaults to 10 milliseconds.
nfsrootdebug
This parameter enables debugging messages to appear in the kernel
diff --git a/net/ipv4/ipconfig.c b/net/ipv4/ipconfig.c
index c56b6fe6f0d7..cbf35163b973 100644
--- a/net/ipv4/ipconfig.c
+++ b/net/ipv4/ipconfig.c
@@ -82,8 +82,6 @@
#define IPCONFIG_DYNAMIC
#endif
-/* Define the friendly delay before and after opening net devices */
-#define CONF_POST_OPEN 10 /* After opening: 10 msecs */
/* Define the timeout for waiting for a DHCP/BOOTP/RARP reply */
#define CONF_OPEN_RETRIES 2 /* (Re)open devices twice */
@@ -101,6 +99,7 @@
/* Wait for carrier timeout default in seconds */
static unsigned int carrier_timeout = 120;
+static unsigned int dev_wait_ms = 10;
/*
* Public IP configuration
@@ -1516,7 +1515,8 @@ static int __init ip_auto_config(void)
return err;
/* Give drivers a chance to settle */
- msleep(CONF_POST_OPEN);
+ if(dev_wait_ms > 0)
+ msleep(dev_wait_ms);
/*
* If the config information is insufficient (e.g., our IP address or
@@ -1849,3 +1849,20 @@ static int __init set_carrier_timeout(char *str)
return 1;
}
__setup("carrier_timeout=", set_carrier_timeout);
+
+
+static int __init set_dev_wait_ms(char *str)
+{
+ ssize_t ret;
+
+ if (!str)
+ return 0;
+
+ ret = kstrtouint(str, 0, &dev_wait_ms);
+ if (ret)
+ return 0;
+
+ return 1;
+}
+
+__setup("ip.dev_wait_ms=", set_dev_wait_ms);
--
2.39.2On Mon, Feb 05, 2024 at 12:44:40PM +0100, David Ventura wrote: > During IP auto configuration, some drivers apparently need to wait a > certain length of time to settle; as this is not true for all drivers, > make this length of time configurable. Do you see this problem with multiple drivers, or just one in particular. To me this seems like a driver bug, and you are just papering over the cracks. Andrew
On 2/5/24 15:06, Andrew Lunn wrote: > On Mon, Feb 05, 2024 at 12:44:40PM +0100, David Ventura wrote: >> During IP auto configuration, some drivers apparently need to wait a >> certain length of time to settle; as this is not true for all drivers, >> make this length of time configurable. > Do you see this problem with multiple drivers, or just one in > particular. To me this seems like a driver bug, and you are just > papering over the cracks. > > Andrew I don't know of any drivers that may need to wait -- I noticed this code path being hit when building a minimal kernel that only had a virtio network device. At least for the virtio device, the wait is unnecessary and bloats the time to boot a minimal kernel from 15ms to 33ms. David
On Mon, Feb 05, 2024 at 03:31:38PM +0100, David wrote: > On 2/5/24 15:06, Andrew Lunn wrote: > > On Mon, Feb 05, 2024 at 12:44:40PM +0100, David Ventura wrote: > > > During IP auto configuration, some drivers apparently need to wait a > > > certain length of time to settle; as this is not true for all drivers, > > > make this length of time configurable. > > Do you see this problem with multiple drivers, or just one in > > particular. To me this seems like a driver bug, and you are just > > papering over the cracks. > > > > Andrew > I don't know of any drivers that may need to wait -- I noticed > this code path being hit when building a minimal kernel that only > had a virtio network device. > At least for the virtio device, the wait is unnecessary and bloats > the time to boot a minimal kernel from 15ms to 33ms. Looking at the code, a delay has been here a long time, since before git. However, 2011 the delay was changes from 1 second to 10ms. There was a discussion about this at the time: https://lore.kernel.org/netdev/1305696161-18277-1-git-send-email-micha@neli.hopto.org/t/ It was said that ARP and DHCP retries should recover any system where the first transmit/receive gets lost with the change from 1s to 10ms. Maybe after 12 years, its time to try a default of 0ms? I would suggest that is a second patch, which is easy to revert if it all goes horribly wrong. Andrew
As suggested, I'm updating the default to 0ms.
This patch depends on 1f0aa0c947eeb4edb60add141a5bc2309f2dc8dd ("
net: make driver settling time configurable").
Signed-off-by: David Ventura <david@davidv.dev>
---
Documentation/admin-guide/nfs/nfsroot.rst | 2 +-
net/ipv4/ipconfig.c | 2 +-
2 files changed, 2 insertions(+), 2 deletions(-)
diff --git a/Documentation/admin-guide/nfs/nfsroot.rst b/Documentation/admin-guide/nfs/nfsroot.rst
index f26f7a342af6..fce610a4ec54 100644
--- a/Documentation/admin-guide/nfs/nfsroot.rst
+++ b/Documentation/admin-guide/nfs/nfsroot.rst
@@ -225,7 +225,7 @@ ip=<client-ip>:<server-ip>:<gw-ip>:<netmask>:<hostname>:<device>:<autoconf>:<dns
ip.dev_wait_ms=<value>
Set the number of milliseconds to delay after opening the network device
- which will be autoconfigured. Defaults to 10 milliseconds.
+ which will be autoconfigured. Defaults to 0 milliseconds.
nfsrootdebug
This parameter enables debugging messages to appear in the kernel
diff --git a/net/ipv4/ipconfig.c b/net/ipv4/ipconfig.c
index cbf35163b973..8b7d08649b09 100644
--- a/net/ipv4/ipconfig.c
+++ b/net/ipv4/ipconfig.c
@@ -99,7 +99,7 @@
/* Wait for carrier timeout default in seconds */
static unsigned int carrier_timeout = 120;
-static unsigned int dev_wait_ms = 10;
+static unsigned int dev_wait_ms = 0;
/*
* Public IP configuration
--
2.39.2On Mon, 5 Feb 2024 16:55:43 +0100 David Ventura wrote:
> As suggested, I'm updating the default to 0ms.
>
> This patch depends on 1f0aa0c947eeb4edb60add141a5bc2309f2dc8dd ("
> net: make driver settling time configurable").
Please post a v2, in a new thread, and proper commit description
with a link to the discussion with Andrew.
On 2/5/24 15:06, Andrew Lunn wrote: > On Mon, Feb 05, 2024 at 12:44:40PM +0100, David Ventura wrote: >> During IP auto configuration, some drivers apparently need to wait a >> certain length of time to settle; as this is not true for all drivers, >> make this length of time configurable. > Do you see this problem with multiple drivers, or just one in > particular. To me this seems like a driver bug, and you are just > papering over the cracks. > > Andrew I haven't seen any problems -- I assumed that some drivers need to wait, given
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