Bug 620364
| Summary: | Parallel dd in tmpfs will failed when the whole memory is pass 1/2 of total memory | ||
|---|---|---|---|
| Product: | Red Hat Enterprise Linux 6 | Reporter: | Joy Pu <ypu> |
| Component: | kernel | Assignee: | mm-maint-bot <mm-maint> |
| kernel sub component: | Memory Management | QA Contact: | Chao Ye <cye> |
| Status: | CLOSED NOTABUG | Docs Contact: | |
| Severity: | medium | ||
| Priority: | low | CC: | agk, cye, jmarchan, wgomerin |
| Version: | 6.1 | Keywords: | RHELNAK |
| Target Milestone: | rc | ||
| Target Release: | --- | ||
| Hardware: | All | ||
| OS: | Linux | ||
| Whiteboard: | |||
| Fixed In Version: | Doc Type: | Bug Fix | |
| Doc Text: | Story Points: | --- | |
| Clone Of: | Environment: | ||
| Last Closed: | 2016-04-11 11:24:22 UTC | Type: | --- |
| 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: | 846704, 1270638 | ||
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Description
Joy Pu
2010-08-02 10:40:55 UTC
This issue has been proposed when we are only considering blocker issues in the current Red Hat Enterprise Linux release. ** If you would still like this issue considered for the current release, ask your support representative to file as a blocker on your behalf. Otherwise ask that it be considered for the next Red Hat Enterprise Linux release. ** Thank you for your bug report. This issue was evaluated for inclusion in the current release of Red Hat Enterprise Linux. Unfortunately, we are unable to address this request in the current release. Because we are in the final stage of Red Hat Enterprise Linux 6 development, only significant, release-blocking issues involving serious regressions and data corruption can be considered. If you believe this issue meets the release blocking criteria as defined and communicated to you by your Red Hat Support representative, please ask your representative to file this issue as a blocker for the current release. Otherwise, ask that it be evaluated for inclusion in the next minor release of Red Hat Enterprise Linux. Since RHEL 6.2 External Beta has begun, and this bug remains unresolved, it has been rejected as it is not proposed as exception or blocker. Red Hat invites you to ask your support representative to propose this request, if appropriate and relevant, in the next release of Red Hat Enterprise Linux. (In reply to Joy Pu from comment #0) > Description: > In the RHEL6.0 host, Parallel dd always failed with "out of memory" warning > when try to allocate a piece of memory which is bigger than 1/2 of physical > memory plus swap. This makes the result of dd is much smaller than expect. > The same test will pass in RHEL 5.5. And this will happen both with > transparent hugepage off and on. > > Version-Release number of selected component (if > applicable):2.6.32-54.el6.x86_64 > > How reproducible: > Always > > Steps to Reproduce: > 1. mount tmpfs(Using 8G as the swap is about 6G and memory is 4G) > mount -t tmpfs -o size=8G none /mnt > 2. Parallel dd > for i in `seq 5`; do dd if=/dev/zero of=/mnt/$i bs=1G count=1 & done This will allocate 5 buffers of 1 GB, and write 5 GB to a filesystem residing in memory. This is not surprising that one can reach an OOM condition under these circumstances. I don't know what changed between RHEL 5 and 6 that would explain the different behavior, but I would not consider that a bug. An obvious workaround is to use a reasonable block size, e.g.: for i in `seq 5`; do dd if=/dev/zero of=/mnt/$i bs=1M count=1024 & done |