Hello,

I tested all day both before and after patching.

I could not understand that it is a memory leak or not. Maybe it needs optimization. You lead, I follow.

1-) You are right, alloc_q is never bigger than 1024. But it always allocates 32 units then more than 1024 are being freed. Maybe it takes time, I don't know.

2-) I tested tx_rs_thresh via ping. After 210 sec , allocated memories are back to mempool (most of them). (driver virtio and eth-devices are binded via igb_uio) . It really takes time. So it is better to increase the size of the mempool. (https://doc.dpdk.org/guides/prog_guide/poll_mode_drv.html)

3-) try to list mempool state in randomly

Test -1 -) (old code) ICMP testing. The whole mempool size is about 10350. So after FIFO reaches max-size -1024, %10 of the size of the mempool is in use. But little by little memory is waiting in use and doesn't go back to the pool. I could not find the reason.

MBUF_POOL 448 9,951 4.31% [|....................]
MBUF_POOL 1,947 8,452 18.72% [||||.................]
MBUF_POOL 1,803 8,596 17.34% [||||.................]
MBUF_POOL 1,941 8,458 18.67% [||||.................]
MBUF_POOL 1,900 8,499 18.27% [||||.................]
MBUF_POOL 1,999 8,400 19.22% [||||.................]
MBUF_POOL 1,724 8,675 16.58% [||||.................]
MBUF_POOL 1,811 8,588 17.42% [||||.................]
MBUF_POOL 1,978 8,421 19.02% [||||.................]
MBUF_POOL 2,008 8,391 19.31% [||||.................]
MBUF_POOL 1,854 8,545 17.83% [||||.................]
MBUF_POOL 1,922 8,477 18.48% [||||.................]
MBUF_POOL 1,892 8,507 18.19% [||||.................]
MBUF_POOL 1,957 8,442 18.82% [||||.................]

Test-2 -) (old code) run iperf3 udp testing that from Kernel to eth device. Waited to see what happens in 4 min. memory doesn't go back to the mempool. little by little, memory usage increases.

MBUF_POOL 512 9,887 4.92% [|....................]
MBUF_POOL 1,411 8,988 13.57% [|||..................]
MBUF_POOL 1,390 9,009 13.37% [|||..................]
MBUF_POOL 1,558 8,841 14.98% [|||..................]
MBUF_POOL 1,453 8,946 13.97% [|||..................]
MBUF_POOL 1,525 8,874 14.66% [|||..................]
MBUF_POOL 1,592 8,807 15.31% [||||.................]
MBUF_POOL 1,639 8,760 15.76% [||||.................]
MBUF_POOL 1,624 8,775 15.62% [||||.................]
MBUF_POOL 1,618 8,781 15.56% [||||.................]
MBUF_POOL 1,708 8,691 16.42% [||||.................]
iperf is STOPPED to tx_fresh for 4 min
MBUF_POOL 1,709 8,690 16.43% [||||.................]
iperf is STOPPED to tx_fresh for 4 min
MBUF_POOL 1,709 8,690 16.43% [||||.................]
MBUF_POOL 1,683 8,716 16.18% [||||.................]
MBUF_POOL 1,563 8,836 15.03% [||||.................]
MBUF_POOL 1,726 8,673 16.60% [||||.................]
MBUF_POOL 1,589 8,810 15.28% [||||.................]
MBUF_POOL 1,556 8,843 14.96% [|||..................]
MBUF_POOL 1,610 8,789 15.48% [||||.................]
MBUF_POOL 1,616 8,783 15.54% [||||.................]
MBUF_POOL 1,709 8,690 16.43% [||||.................]
MBUF_POOL 1,740 8,659 16.73% [||||.................]
MBUF_POOL 1,546 8,853 14.87% [|||..................]
MBUF_POOL 1,710 8,689 16.44% [||||.................]
MBUF_POOL 1,787 8,612 17.18% [||||.................]
MBUF_POOL 1,579 8,820 15.18% [||||.................]
MBUF_POOL 1,780 8,619 17.12% [||||.................]
MBUF_POOL 1,679 8,720 16.15% [||||.................]
MBUF_POOL 1,604 8,795 15.42% [||||.................]
MBUF_POOL 1,761 8,638 16.93% [||||.................]
MBUF_POOL 1,773 8,626 17.05% [||||.................]

Test-3 -) (after patching) run iperf3 udp testing that from Kernel to eth device. looks stable.

After patching ,

MBUF_POOL 76 10,323 0.73% [|....................]
MBUF_POOL 193 10,206 1.86% [|....................]
MBUF_POOL 96 10,303 0.92% [|....................]
MBUF_POOL 269 10,130 2.59% [|....................]
MBUF_POOL 102 10,297 0.98% [|....................]
MBUF_POOL 235 10,164 2.26% [|....................]
MBUF_POOL 87 10,312 0.84% [|....................]
MBUF_POOL 293 10,106 2.82% [|....................]
MBUF_POOL 99 10,300 0.95% [|....................]
MBUF_POOL 296 10,103 2.85% [|....................]
MBUF_POOL 90 10,309 0.87% [|....................]
MBUF_POOL 299 10,100 2.88% [|....................]
MBUF_POOL 86 10,313 0.83% [|....................]
MBUF_POOL 262 10,137 2.52% [|....................]
MBUF_POOL 81 10,318 0.78% [|....................]
MBUF_POOL 81 10,318 0.78% [|....................]
MBUF_POOL 87 10,312 0.84% [|....................]
MBUF_POOL 252 10,147 2.42% [|....................]
MBUF_POOL 97 10,302 0.93% [|....................]
iperf is STOPPED to tx_fresh for 4 min
MBUF_POOL 296 10,103 2.85% [|....................]
MBUF_POOL 95 10,304 0.91% [|....................]
MBUF_POOL 269 10,130 2.59% [|....................]
MBUF_POOL 302 10,097 2.90% [|....................]
MBUF_POOL 88 10,311 0.85% [|....................]
MBUF_POOL 305 10,094 2.93% [|....................]
MBUF_POOL 88 10,311 0.85% [|....................]
MBUF_POOL 290 10,109 2.79% [|....................]
MBUF_POOL 84 10,315 0.81% [|....................]
MBUF_POOL 85 10,314 0.82% [|....................]
MBUF_POOL 291 10,108 2.80% [|....................]
MBUF_POOL 303 10,096 2.91% [|....................]
MBUF_POOL 92 10,307 0.88% [|....................]

Best regards.

Ferruh Yigit <ferruh.yigit@amd.com>, 18 May 2023 Per, 17:56 tarihinde şunu yazdı:

On 5/18/2023 9:14 AM, Yasin CANER wrote:
> Hello Ferruh,
>
> Thanks for your kind response. Also thanks to Stephen.
>
> Even if 1 packet is consumed from the kernel , each time rx_kni
> allocates another 32 units. After a while all mempool is used in alloc_q
> from kni. there is not any room for it.
>

What you described continues until 'alloc_q' is full, by default fifo
length is 1024 (KNI_FIFO_COUNT_MAX), do you allocate less mbuf in your
mempool?

You can consider either increasing mempool size, or decreasing 'alloc_q'
fifo length, but reducing fifo size may cause performance issues so you
need to evaluate that option.

> Do you think my mistake is using one and common mempool usage both kni
> and eth?
>

Using same mempool for both is fine.

> If it needs a separate mempool , i'd like to note in docs.
>
> Best regards.
>
> Ferruh Yigit <ferruh.yigit@amd.com <mailto:ferruh.yigit@amd.com>>, 17
> May 2023 Çar, 20:53 tarihinde şunu yazdı:
>
> On 5/9/2023 12:13 PM, Yasin CANER wrote:
> > Hello,
> >
> > I draw a flow via asciiflow to explain myself better. Problem is after
> > transmitting packets(mbufs) , it never puts in the kni->free_q to back
> > to the original pool. Each cycle, it allocates another 32 units that
> > cause leaks. Or I am missing something.
> >
> > I already tried the rte_eth_tx_done_cleanup() function but it
> didn't fix
> > anything.
> >
> > I am working on a patch to fix this issue but I am not sure if there
> > is another way.
> >
> > Best regards.
> >
> > https://pastebin.ubuntu.com/p/s4h5psqtgZ/
> <https://pastebin.ubuntu.com/p/s4h5psqtgZ/>
> > <https://pastebin.ubuntu.com/p/s4h5psqtgZ/
> <https://pastebin.ubuntu.com/p/s4h5psqtgZ/>>
> >
> >
> > unsigned
> > rte_kni_rx_burst(struct rte_kni *kni, struct rte_mbuf **mbufs,
> unsigned
> > int num)
> > {
> > unsigned int ret = kni_fifo_get(kni->tx_q, (void **)mbufs, num);
> >
> > /* If buffers removed, allocate mbufs and then put them into
> alloc_q */
> > /* Question, how to test buffers is removed or not?*/
> > if (ret)
> > kni_allocate_mbufs(kni);
> >
> > return ret;
> > }
> >
>
> Selam Yasin,
>
>
> You can expect 'kni->alloc_q' fifo to be full, this is not a memory
> leak.
>
> As you pointed out, number of mbufs consumed by kernel from 'alloc_q'
> and number of mbufs added to 'alloc_q' is not equal and this is
> expected.
>
> Target here is to prevent buffer underflow from kernel perspective, so
> it will always have available mbufs for new packets.
> That is why new mbufs are added to 'alloc_q' at worst same or sometimes
> higher rate than it is consumed.
>
> You should calculate your mbuf requirement with the assumption that
> 'kni->alloc_q' will be full of mbufs.
>
>
> 'kni->alloc_q' is freed when kni is removed.
> Since 'alloc_q' holds physical address of the mbufs, it is a little
> challenging to free them in the userspace, that is why first kernel
> tries to move mbufs to 'kni->free_q' fifo, please check
> 'kni_net_release_fifo_phy()' for it.
>
> If all moved to 'free_q' fifo, nothing left to in 'alloc_q', but if not,
> userspace frees 'alloc_q' in 'rte_kni_release()', with following call:
> `kni_free_fifo_phy(kni->pktmbuf_pool, kni->alloc_q);`
>
>
> I can see you have submitted fixes for this issue, although as I
> explained above I don't think a defect exist, I will review them
> today/tomorrow.
>
> Regards,
> Ferruh
>
>
> > Stephen Hemminger <stephen@networkplumber.org
> <mailto:stephen@networkplumber.org>
> > <mailto:stephen@networkplumber.org
> <mailto:stephen@networkplumber.org>>>, 8 May 2023 Pzt, 19:18 tarihinde
> > şunu yazdı:
> >
> > On Mon, 8 May 2023 09:01:41 +0300
> > Yasin CANER <yasinncaner@gmail.com
> <mailto:yasinncaner@gmail.com> <mailto:yasinncaner@gmail.com
> <mailto:yasinncaner@gmail.com>>>
> > wrote:
> >
> > > Hello Stephen,
> > >
> > > Thank you for response, it helps me a lot. I understand problem
> > better.
> > >
> > > After reading mbuf library (
> > > https://doc.dpdk.org/guides/prog_guide/mempool_lib.html
> <https://doc.dpdk.org/guides/prog_guide/mempool_lib.html>
> > <https://doc.dpdk.org/guides/prog_guide/mempool_lib.html
> <https://doc.dpdk.org/guides/prog_guide/mempool_lib.html>>) i
> > realized that
> > > 31 units allocation memory slot doesn't return to pool!
> >
> > If receive burst returns 1 mbuf, the other 31 pointers in the
> array
> > are not valid. They do not point to mbufs.
> >
> > > 1 unit mbuf can be freed via rte_pktmbuf_free so it can back
> to pool.
> > >
> > > Main problem is that allocation doesn't return to original pool,
> > act as
> > > used. So, after following rte_pktmbuf_free
> > >
> >
>   <http://doc.dpdk.org/api/rte__mbuf_8h.html#a1215458932900b7cd5192326fa4a6902 <http://doc.dpdk.org/api/rte__mbuf_8h.html#a1215458932900b7cd5192326fa4a6902> <http://doc.dpdk.org/api/rte__mbuf_8h.html#a1215458932900b7cd5192326fa4a6902 <http://doc.dpdk.org/api/rte__mbuf_8h.html#a1215458932900b7cd5192326fa4a6902>>>
> > > function,
> > > i realized that there is 2 function to helps to mbufs back
> to pool.
> > >
> > > These are rte_mbuf_raw_free
> > >
> >
>   <http://doc.dpdk.org/api/rte__mbuf_8h.html#a9f188d53834978aca01ea101576d7432 <http://doc.dpdk.org/api/rte__mbuf_8h.html#a9f188d53834978aca01ea101576d7432> <http://doc.dpdk.org/api/rte__mbuf_8h.html#a9f188d53834978aca01ea101576d7432 <http://doc.dpdk.org/api/rte__mbuf_8h.html#a9f188d53834978aca01ea101576d7432>>>
> > > and rte_pktmbuf_free_seg
> > >
> >
>   <http://doc.dpdk.org/api/rte__mbuf_8h.html#a006ee80357a78fbb9ada2b0432f82f37 <http://doc.dpdk.org/api/rte__mbuf_8h.html#a006ee80357a78fbb9ada2b0432f82f37> <http://doc.dpdk.org/api/rte__mbuf_8h.html#a006ee80357a78fbb9ada2b0432f82f37 <http://doc.dpdk.org/api/rte__mbuf_8h.html#a006ee80357a78fbb9ada2b0432f82f37>>>.
> > > I will focus on them.
> > >
> > > If there is another suggestion, I will be very pleased.
> > >
> > > Best regards.
> > >
> > > Yasin CANER
> > > Ulak
> >
>