Re: [Intel-wired-lan] Increased memory usage on NUMA nodes with ICE driver after upgrade to 6.13.y (regression in commit 492a044508ad)

[Michal Kubiak <michal.kubiak@intel.com>]

On Mon, Apr 14, 2025 at 06:29:01PM +0200, Jaroslav Pulchart wrote:
> Hello,
> 
> While investigating increased memory usage after upgrading our
> host/hypervisor servers from Linux kernel 6.12.y to 6.13.y, I observed
> a regression in available memory per NUMA node. Our servers allocate
> 60GB of each NUMA node’s 64GB of RAM to HugePages for VMs, leaving 4GB
> for the host OS.
> 
> After the upgrade, we noticed approximately 500MB less free RAM on
> NUMA nodes 0 and 2 compared to 6.12.y, even with no VMs running (just
> the host OS after reboot). These nodes host Intel 810-XXV NICs. Here's
> a snapshot of the NUMA stats on vanilla 6.13.y:
> 
>      NUMA nodes:  0     1     2     3     4     5     6     7     8
>  9    10    11    12    13    14    15
>      HPFreeGiB:   60    60    60    60    60    60    60    60    60
>  60   60    60    60    60    60    60
>      MemTotal:    64989 65470 65470 65470 65470 65470 65470 65453
> 65470 65470 65470 65470 65470 65470 65470 65462
>      MemFree:     2793  3559  3150  3438  3616  3722  3520  3547  3547
>  3536  3506  3452  3440  3489  3607  3729
> 
> We traced the issue to commit 492a044508ad13a490a24c66f311339bf891cb5f
> "ice: Add support for persistent NAPI config".
> 
> We limit the number of channels on the NICs to match local NUMA cores
> or less if unused interface (from ridiculous 96 default), for example:
>    ethtool -L em1 combined 6       # active port; from 96
>    ethtool -L p3p2 combined 2      # unused port; from 96
> 
> This typically aligns memory use with local CPUs and keeps NUMA-local
> memory usage within expected limits. However, starting with kernel
> 6.13.y and this commit, the high memory usage by the ICE driver
> persists regardless of reduced channel configuration.
> 
> Reverting the commit restores expected memory availability on nodes 0
> and 2. Below are stats from 6.13.y with the commit reverted:
>     NUMA nodes:  0     1     2     3     4     5     6     7     8
> 9    10    11    12    13    14    15
>     HPFreeGiB:   60    60    60    60    60    60    60    60    60
> 60   60    60    60    60    60    60
>     MemTotal:    64989 65470 65470 65470 65470 65470 65470 65453 65470
> 65470 65470 65470 65470 65470 65470 65462
>     MemFree:     3208  3765  3668  3507  3811  3727  3812  3546  3676  3596 ...
> 
> This brings nodes 0 and 2 back to ~3.5GB free RAM, similar to kernel
> 6.12.y, and avoids swap pressure and memory exhaustion when running
> services and VMs.
> 
> I also do not see any practical benefit in persisting the channel
> memory allocation. After a fresh server reboot, channels are not
> explicitly configured, and the system will not automatically resize
> them back to a higher count unless manually set again. Therefore,
> retaining the previous memory footprint appears unnecessary and
> potentially harmful in memory-constrained environments
> 
> Best regards,
> Jaroslav Pulchart
> 


Hello Jaroslav,

I have just sent a series for converting the Rx path of the ice driver
to use the Page Pool.
We suspect it may help for the memory consumption issue since it removes
the problematic code and delegates some memory management to the generic
code.

Could you please give it a try and check if it helps for your issue.
The link to the series: https://lore.kernel.org/intel-wired-lan/20250704161859.871152-1-michal.kubiak@intel.com/

Thanks,
Michal