Hello,
Thank you for your answers.
It's unfortunate that by default the irdma module uses an extra 5Gb of
RAM, which is huge (more than 30% of the available RAM) and that there's
practically no way of reducing it without deactivating the module since
the limits_sel parameter is not available in the in-tree driver, as
mentioned by Shiraz (I can confirm that gen1_limits_sel=0 works on
my x722 card, I tested it, but it looks out of topic for me since it's
not in the tree).
For my case, since I don't need the irdma module, I will just blacklist
it as suggested, but I think that it would be better to change the
default value of the resource limit selector so it doesn't consume this
much RAM if it's not used.
On 5/8/24 03:24, Saleem, Shiraz wrote:
Subject: Re: Excessive memory usage when infiniband config is enabled
On Tue, May 07, 2024 at 05:24:51PM +0200, Zhu Yanjun wrote:
在 2024/5/7 15:32, Konstantin Taranov 写道:
Hello Leon,
I feel that it's a bug because I don't understand why is this
module/option allocating 6GB of RAM without any explicit configuration or
usage from us.
It's also worth mentioning that we are using the default
linux-image from Debian bookworm, and it took us a long time to
understand the reason behind this memory increase by bisecting the
kernel's config file.
Moreover the documentation of the module doesn't mention anything
regarding additional memory usage, we're talking about an increase
of 6Gb which is huge since we're not using the option.
So is that an expected behavior, to have this much increase in the
memory consumption, when activating the RDMA option even if we're
not using it ? If that's the case, perhaps it would be good to
mention this in the documentation.
Thank you
Hi Brian,
I do not think it is a bug. The high memory usage seems to come from these
lines:
rsrc_size = irdma_calc_mem_rsrc_size(rf);
rf->mem_rsrc = vzalloc(rsrc_size);
Exactly. The memory usage is related with the number of QP.
When on irdma, the Queue Pairs is 4092, Completion Queues is 8189, the
memory usage is about 4194302.
The command "modprobe irdma limits_sel" will change QP numbers.
0 means minimum, up to 124 QPs.
Please use the command "modprobe irdma limits_sel=0" to make tests.
Please let us know the test results.
It seems like a really unfortunate design choice in this driver to not have dynamic
memory allocation.
Burning 6G on every server that has your HW, regardless if any RDMA apps are
run, seems completely excessive.
So the driver requires to pre-allocate backing pages for HW context objects during device initialization. At least for the x722 and e800 series product lines.
And the amount of memory allocated is proportional to the max QP (primarily) setup for the function.
One option is to set a lower default profile upon driver loading; which will reduce the memory footprint; but exposes lower QP and other verb resources per ib_device.
And provide users with a devlink knob to choose a larger/smaller profile as they see fit.
This is sort of what limits_sel module parameter Yanjun suggested realizes, but it is not available in the in-tree driver.
Between, what is the specific Intel NIC model in use?
lspci -vv | grep -E 'Eth.*Intel|Product'
Shiraz
