Re: [libvirt] problem with outbound limiting

Thanks for your clarification. I am using 2.6.38-8-server kernel. Will test with 3.0.0 kernel

On Thu, Aug 11, 2011 at 7:18 PM, Stefan Berger <stefanb(a)linux.vnet.ibm.com&gt; wrote: > On 08/11/2011 09:39 AM, Stefan Berger wrote: >> On 08/11/2011 08:07 AM, Upendra Moturi wrote: >>> Thanks for your reply. >>> >>> The patch it appears still has problem. >>> I have changed only mtu value as 2kb instead of burst value in the >>> network.c file >>> >>> With average as 2048 , burst as 2048 and peak 2048 >>> scp copied at 30-40KB/s >> All test I did were with the patch applied. I saw the throughput >> collapsing yesterday at 2Mb mtu. > Let me clarify : Yesterday I saw the throughput collapse without the patch > applied. > > Stefan > >> I generated a file using >> >> dd if=/dev/urandom of=testfile bs=1024 count=409600 >> >> I did the same test you did with 2048 without specifying a specific model >> of ethernet card and reach 1.9MB/s using scp'ing towards remote machine. >> When specifying<model type='virtio'/> I also get 1.9MB/s as result. >>> With average as 4096 , burst as 4096 and peak 4096 >>> scp copied at same 30-40KB/s >>> >> With these numbers and using the virtio model I ended up getting a >> throughput of 3.8Mb/s. >> >> The host is a 3.0.0 Linux kernel. Here's the command line output of the tc >> command inspecting the tap interface of the VM (vnet0). >> >> # tc filter show dev vnet0 root >> filter parent ffff: protocol ip pref 49152 u32 >> filter parent ffff: protocol ip pref 49152 u32 fh 800: ht divisor 1 >> filter parent ffff: protocol ip pref 49152 u32 fh 800::800 order 2048 key >> ht 800 bkt 0 flowid :1 >> match 00000000/00000000 at 12 >> police 0x5b rate 32768Kbit burst 4Mb mtu 2Kb action drop overhead 0b >> ref 1 bind 1 >> >> >> Maybe someone else can verify as well. >> >> Stefan >> >>> where as earlier it was 1 MB/s.(without patch) >>> >>> On Wed, Aug 10, 2011 at 9:16 PM, Stefan Berger >>> <stefanb(a)linux.vnet.ibm.com&gt; wrote: >>>> On 08/10/2011 11:20 AM, Eric Blake wrote: >>>>> On 08/10/2011 09:04 AM, Stefan Berger wrote: >>>>>> On 08/10/2011 02:55 AM, Upendra Moturi wrote: >>>>>> >>>>>> Hi, >>>>>> >>>>>> does this patch solve your problem? I am setting the MTU to fixed 2kb. >>>>>> Doing tests with scp seems to indicate that this improved the >>>>>> situation >>>>>> -- at least for me. >>>>>> >>>>>> Stefan >>>>>> >>>>>> Signed-off-by: Stefan Berger&lt;stefanb(a)linux.vnet.ibm.com&gt; >>>>>> >>>>>> --- >>>>>> src/util/network.c | 16 ++++++++-------- >>>>>> 1 file changed, 8 insertions(+), 8 deletions(-) >>>>>> >>>>>> Index: libvirt-acl/src/util/network.c >>>>>> =================================================================== >>>>>> --- libvirt-acl.orig/src/util/network.c >>>>>> +++ libvirt-acl/src/util/network.c >>>>>> @@ -1156,8 +1156,8 @@ virBandwidthEnable(virBandwidthPtr bandw >>>>>> >>>>>> virCommandFree(cmd); >>>>>> cmd = virCommandNew(TC); >>>>>> - virCommandAddArgList(cmd,"class", "add", "dev", iface, "parent", >>>>>> - "1:", "classid", "1:1", "htb", NULL); >>>>>> + virCommandAddArgList(cmd,"class", "add", "dev", iface, "parent", >>>>>> + "1:", "classid", "1:1", "htb", NULL); >>>>>> virCommandAddArgList(cmd, "rate", average, NULL); >>>>> This hunk was just indentation; you should push the whitespace changes >>>>> as >>>>> a separate commit (and can push that now, under the trivial rule, >>>>> without >>>>> needing further review). [It doesn't help matters that thunderbird >>>>> botched >>>>> the whitespace in my reply] >>>>> >>>>>> @@ -1202,7 +1202,7 @@ virBandwidthEnable(virBandwidthPtr bandw >>>>>> virCommandAddArgList(cmd, "filter", "add", "dev", iface, "parent", >>>>>> "ffff:", "protocol", "ip", "u32", "match", "ip", >>>>>> "src", "0.0.0.0/0", "police", "rate", average, >>>>>> - "burst", burst, "mtu", burst, "drop", "flowid", >>>>>> + "burst", burst, "mtu", "2kb", "drop", "flowid", >>>>>> ":1", NULL); >>>>> Here's the meat of the proposed patch. Is 2kb always valid, or will we >>>>> run into problems on NICs that insist on traditional limits near the >>>>> 1518 >>>>> mark? Should it be user-configurable? I'm reluctant to ACK this >>>>> without a >>>>> bit more understanding of why 2kb works, as well as feedback on test >>>>> results >>>>> with the patch in place. >>>>> >>>> Yes, I am not an exper on tc. I have seen examples with the mtu being >>>> set to >>>> '1' for dropping icmp traffic for example. So if a VM produces smaller >>>> than >>>> 2kb packets, which on traditional networks it probably should, then the >>>> packets should go through. We could also leave out the mtu parameter >>>> above >>>> and it would go to 2kb by default. Check via >>>> >>>> tc filter show dev<ifname> root >>>> >>>> The 2kb parameter doesn't explain why 2MB doesn't work, though. >>>> Even if this wasn't the final fix, it at least 'improves the situation' >>>> (for >>>> me). >>>> >>>> Stefan >>>> >>>> >>>> >>> >> -- >> libvir-list mailing list >> libvir-list(a)redhat.com >> https://www.redhat.com/mailman/listinfo/libvir-list > -- > libvir-list mailing list > libvir-list(a)redhat.com > https://www.redhat.com/mailman/listinfo/libvir-list >