qemu_vm.py: update vhost thread matching pattern and process command #3971

quanwenli · 2024-08-13T09:57:04Z

- switched to using "ps -eL" for vhost thread detection, as vhost
threads are now created as separate threads and no longer appear in
"ps aux" output in the latest kernel. "ps -eL" also works with older
kernels.
- fix vhost_thread_pattern to capture LWP from "ps -eL" output

Signed-off-by: Wenli Quan [email protected]

id: 2774

quanwenli · 2024-08-13T10:01:32Z

JOB LOG : /root/avocado/job-results/job-2024-08-13T05.36-c371659/job.log
(1/1) BF3.bridge_test.1q.acceptance.repeat1.Host_RHEL.m10.u0.qcow2.virtio_blk.up.virtio_net.Guest.RHEL.9.5.0.x86_64.io-github-autotest-qemu.netperf.default.host_guest.q35: STARTED
(1/1) BF3.bridge_test.1q.acceptance.repeat1.Host_RHEL.m10.u0.qcow2.virtio_blk.up.virtio_net.Guest.RHEL.9.5.0.x86_64.io-github-autotest-qemu.netperf.default.host_guest.q35: PASS (205.84 s)
RESULTS : PASS 1 | ERROR 0 | FAIL 0 | SKIP 0 | WARN 0 | INTERRUPT 0 | CANCEL 0
JOB HTML : /root/avocado/job-results/job-2024-08-13T05.36-c371659/results.html

quanwenli · 2024-08-13T10:01:54Z

@YongxueHong could you help review it. thanks a lot.

YongxueHong · 2024-09-02T14:56:52Z

Hi, @leidwang @fbq815 @zhenyzha @yanglei-rh @PaulYuuu
Could you help to review it? Thanks a lot.

YongxueHong · 2024-09-02T14:44:47Z

virttest/qemu_vm.py

@@ -3945,7 +3945,7 @@ def create(
                    ", ".join([str(tid) for tid in self.vcpu_threads]),
                )
            vhost_thread_pattern = params.get(
-                "vhost_thread_pattern", r"\w+\s+(\d+)\s.*\[vhost-%s\]"
+                "vhost_thread_pattern", r"\w+\s+(\d+)\s.*\[*vhost-%s\]*"


Hi, @quanwenli
Could you provide the example output of both situations?
Thanks.
CC @leidwang @PaulYuuu , it maybe affect your test case.

Hi @YongxueHong I guess you'd like to ping me istead of @leidwang. And the code looks good to me.

on old system:
ps aux | grep host
root 331500 24.8 0.0 0 0 ? R 22:29 0:18 [vhost-331496]
ps -eL | grep host
331500 331500 ? 00:00:27 vhost-331496

The matched group is not the same one. The old pattern matches "PID" from ps aux, but the new pattern matches "LWP" from ps -eL, In your sanity test, they are the same, but cannot mark sure they are always the same.

Header of ps -eL and ps aux

# ps -eL PID LWP TTY TIME CMD 1 1 pts/0 00:00:00 bash 37 37 pts/0 00:00:00 ps # ps aux USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND root 1 0.0 0.0 4832 3656 pts/0 Ss 02:44 0:00 /bin/bash root 38 0.0 0.0 7708 3704 pts/0 R+ 02:48 0:00 ps aux

I suggest changing the pattern accordingly.

YongxueHong

LGTM

YongxueHong · 2024-09-11T07:36:46Z

Hi, @leidwang @fbq815 @zhenyzha @PaulYuuu
Just for a kindly reminding. Could you help to review it from your perspective?
Thanks

fbq815

zhenyzha · 2024-09-20T11:35:33Z

multi_queues_test.invalid_queues_number.upper_border.arm64-pci: PASS (36.69 s)

LGTM.Acked-by: Zhenyu Zhang [email protected]

PaulYuuu · 2024-09-25T08:30:08Z

virttest/qemu_vm.py

@@ -4396,7 +4396,7 @@ def get_vhost_threads(self, vhost_thread_pattern):
            int(_)
            for _ in re.findall(
                vhost_thread_pattern % self.get_pid(),
-                process.run("ps aux", verbose=False).stdout_text,
+                process.run("ps -eL", verbose=False).stdout_text,


The help info from ps:

# ps --help threads Usage: ps [options] Show threads: H as if they were processes -L possibly with LWP and NLWP columns -m, m after processes -T possibly with SPID column

I think ps -e is enough in this place. the -L option has different behavior in different OS. With this change. We should also test multiqueues cases to make sure no regression.

I just confirmed with the developer that we need to get the LWP values for the vhost threads. Additionally, I checked on the latest system and found that there are no vhost thread ids returned by the “ps -e” command. Therefore, “ps -eL” is needed in the code and I also update the pattern. please help review.

on rhel9.5:
ps -eL |grep vhost
2922 2922 ? 00:00:00 vhost-2918
2923 2923 ? 00:00:00 vhost-2918
2924 2924 ? 00:00:00 vhost-2918
2925 2925 ? 00:00:00 vhost-2918
ps -e |grep vhost
2922 ? 00:00:00 vhost-2918
2923 ? 00:00:00 vhost-2918
2924 ? 00:00:00 vhost-2918
2925 ? 00:00:00 vhost-2918

on latest system:
ps -e |grep vhost
ps -eL |grep vhost
186773 186784 pts/1 00:00:00 vhost-186773
186773 186785 pts/1 00:00:00 vhost-186773
186773 186786 pts/1 00:00:00 vhost-186773
186773 186788 pts/1 00:00:00 vhost-186773

Ok, this means the kernel behavior changes from 1 vhost per process to 1 vhost per thread. However, I see that you modified the pattern to match LWP instead of PID, which is different from the original pattern, can you explain?

From ps man page: LWP means light weight process (thread) ID of the dispatchable entity (alias spid, tid).

As I mentioned before, I confirmed with developer, we need to check the vhost thread ID from LWP. and also you can see the output on latest system with a vm with 4 queues, the pid is the only one but four LWP are the different, so, the pattern should be adjusted to correctly match the LWP.

Some means you want TID, not PID now. This should be a change, we need to update the doc string.

I have updated the both doc string and git commit. please help review.

- switched to using "ps -eL" for vhost thread detection, as vhost threads are now created as separate threads and no longer appear in "ps aux" output in the latest kernel. "ps -eL" also works with older kernels. - fix vhost_thread_pattern to capture LWP from "ps -eL" output Signed-off-by: Wenli Quan <[email protected]>

quanwenli · 2024-09-27T09:20:43Z

JOB LOG : /root/avocado/job-results/job-2024-09-25T03.36-43de120/job.log
(1/1) 82599.bridge_test.1q.acceptance.repeat1.Host_RHEL.m9.u5.qcow2.virtio_blk.up.virtio_net.Guest.RHEL.9.5.0.x86_64.io-github-autotest-qemu.netperf.default.host_guest.q35: STARTED
(1/1) 82599.bridge_test.1q.acceptance.repeat1.Host_RHEL.m9.u5.qcow2.virtio_blk.up.virtio_net.Guest.RHEL.9.5.0.x86_64.io-github-autotest-qemu.netperf.default.host_guest.q35: PASS (679.59 s)
RESULTS : PASS 1 | ERROR 0 | FAIL 0 | SKIP 0 | WARN 0 | INTERRUPT 0 | CANCEL 0
JOB HTML : /root/avocado/job-results/job-2024-09-25T03.36-43de120/results.html
JOB TIME : 681.18 s

yanglei-rh

LGTM

YongxueHong · 2024-09-29T02:32:33Z

The only thing we need to take care of is updating the regex with the accurate pattern for multi_queues_test.py test case since we modified the implementation here.
Although the pattern does work now, there is still a potential issue here, I suggest updating it later.
CC @yanglei-rh @PaulYuuu @zhenyzha @fbq815
Thanks.

YongxueHong reviewed Sep 2, 2024

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YongxueHong approved these changes Sep 11, 2024

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fbq815 approved these changes Sep 20, 2024

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zhenyzha approved these changes Sep 20, 2024

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quanwenli force-pushed the vhost branch from b278de9 to 8078b46 Compare September 25, 2024 07:48

PaulYuuu reviewed Sep 25, 2024

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quanwenli force-pushed the vhost branch from 8078b46 to bb5c85c Compare September 25, 2024 10:02

quanwenli force-pushed the vhost branch from bb5c85c to b69ca8f Compare September 27, 2024 08:10

PaulYuuu approved these changes Sep 27, 2024

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yanglei-rh approved these changes Sep 29, 2024

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YongxueHong approved these changes Sep 29, 2024

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YongxueHong merged commit 572bdac into avocado-framework:master Sep 29, 2024
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qemu_vm.py: update vhost thread matching pattern and process command #3971

qemu_vm.py: update vhost thread matching pattern and process command #3971

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qemu_vm.py: update vhost thread matching pattern and process command #3971

qemu_vm.py: update vhost thread matching pattern and process command #3971

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