Bug 1883753
| Summary: | [RHEL8.6] Makedumpfile gets estimated vmcore size with specified options | |||
|---|---|---|---|---|
| Product: | Red Hat Enterprise Linux 8 | Reporter: | lijiang | |
| Component: | kexec-tools | Assignee: | Philipp Rudo <prudo> | |
| Status: | CLOSED ERRATA | QA Contact: | Jie Li <jieli> | |
| Severity: | unspecified | Docs Contact: | Sujata Kurup <skurup> | |
| Priority: | unspecified | |||
| Version: | 8.4 | CC: | jieli, ltao, prudo, ruyang, skurup, xiawu, yiyan | |
| Target Milestone: | rc | Keywords: | FutureFeature, Triaged | |
| Target Release: | 8.0 | |||
| Hardware: | Unspecified | |||
| OS: | Unspecified | |||
| Whiteboard: | ||||
| Fixed In Version: | kexec-tools-2.0.20-48.el8 | Doc Type: | If docs needed, set a value | |
| Doc Text: | Story Points: | --- | ||
| Clone Of: | ||||
| : | 1958452 2017314 2017319 (view as bug list) | Environment: | ||
| Last Closed: | 2022-05-10 15:23:50 UTC | Type: | Bug | |
| Regression: | --- | Mount Type: | --- | |
| Documentation: | --- | CRM: | ||
| Verified Versions: | Category: | --- | ||
| oVirt Team: | --- | RHEL 7.3 requirements from Atomic Host: | ||
| Cloudforms Team: | --- | Target Upstream Version: | ||
| Embargoed: | ||||
| Bug Depends On: | ||||
| Bug Blocks: | 1674330, 1868698, 1958452, 2017314, 2017319 | |||
|
Description
lijiang
2020-09-30 07:05:21 UTC
As we discussed in the meeting, the '--mem-usage' option has a conflict with other options and it costs time as below: # time makedumpfile /proc/kcore --mem-usage The kernel version is not supported. The makedumpfile operation may be incomplete. TYPE PAGES EXCLUDABLE DESCRIPTION ---------------------------------------------------------------------- ZERO 48065 yes Pages filled with zero NON_PRI_CACHE 204748 yes Cache pages without private flag PRI_CACHE 153 yes Cache pages with private flag USER 23906 yes User process pages FREE 7689812 yes Free pages KERN_DATA 291289 no Dumpable kernel data page size: 4096 Total pages on system: 8257973 Total size on system: 33824657408 Byte real 0m9.535s user 0m1.450s sys 0m8.074s Therefore, it could be good to add a new option '--vmcore-size', which will get a value of estimated vmcore size and do not need to actually save the vmcore(only compute the size of vmcore): #makedumpfile -l --message-level 1 -d 31 /proc/kcore vmcore --vmcore-size # time makedumpfile -l --message-level 1 -d 31 /proc/kcore vmcore --vmcore-size Copying data : [ 67.1 %] - eta: 1s real 0m2.801s user 0m1.851s sys 0m0.943s The performance could be improved because the vmcore is not actually saved. > Therefore, it could be good to add a new option '--vmcore-size', which will
> get a value of estimated vmcore size and do not need to actually save the
> vmcore(only compute the size of vmcore):
>
The --mem-usage can not estimate the compressed size, so the idea is to add a new option to do go through the saving process but do not save data only return the final saved size, something like save to /dev/null etc.
It is still not enough to estimate a vmcore size since vmcore size depends on the system memory use and workload, people may need to periodicity monitor the vmcore size and the remain space of dump target. Anyway it is still a best effort but it is better than none like before.
The patch [1][2][3] implemented option --dry-run and --show-stats:
# makedumpfile -l --message-level 1 -d 31 /proc/kcore vmcore --dry-run --show-stats
Checking for memory holes : [100.0 %] | STEP [Checking for memory holes ] : 0.000071 seconds
Excluding unnecessary pages : [100.0 %] \ STEP [Excluding unnecessary pages] : 0.268348 seconds
Checking for memory holes : [100.0 %] - STEP [Checking for memory holes ] : 0.000372 seconds
Checking for memory holes : [100.0 %] / STEP [Checking for memory holes ] : 0.000032 seconds
Excluding unnecessary pages : [100.0 %] | STEP [Excluding unnecessary pages] : 0.264383 seconds
Copying data : [ 84.2 %] | eta: 0sSTEP [Copying data ] : 3.926611 seconds
STEP [Copying data ] : 0.000000 seconds
Original pages : 0x00000000007f32ba
Excluded pages : 0x00000000007520c7
Pages filled with zero : 0x0000000000011c49
Non-private cache pages : 0x00000000000b9cd5
Private cache pages : 0x0000000000086f4e
User process data pages : 0x000000000011cd44
Free pages : 0x00000000004e2b17
Hwpoison pages : 0x0000000000000000
Offline pages : 0x0000000000000000
Remaining pages : 0x00000000000a11f3
(The number of pages is reduced to 7%.)
Memory Hole : 0x000000000005cd46
--------------------------------------------------
Total pages : 0x0000000000850000
Write bytes : 1273508345
Cache hit: 738293, miss: 967362, hit rate: 43.3%
--dry-run asks makedumpfile don't write data into disk, --show-stats will print report messages.
the "Write bytes" provide an value of the vmcore size. The value may have slight differences
between each run. So it can estimate the vmcore size when dry-run.
[1] https://www.mail-archive.com/kexec@lists.infradead.org/msg25485.html
[2] https://www.mail-archive.com/kexec@lists.infradead.org/msg25484.html
[3] https://github.com/makedumpfile/makedumpfile/commit/0ef2ca6c9fa2f61f217a4bf5d7fd70f24e12b2eb
I verified that the code was included with rhel 8.5 kexec-tools-2.0.20-48.el8 and works with the flaws described in comment 43, for which separate bugs where opened in comment 46. The same holds for the latest rhel 8.6 kexec-tools-2.0.20-63.el8 build. @Jie: can you take over from here? Since the problem described in this bug report should be resolved in a recent advisory, it has been closed with a resolution of ERRATA. For information on the advisory (kexec-tools bug fix and enhancement update), and where to find the updated files, follow the link below. If the solution does not work for you, open a new bug report. https://access.redhat.com/errata/RHBA-2022:2053 |