Bug 101660
Summary: | O_DIRECT seems to chew up (not release) a ton of memory | ||||||||||
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Product: | Red Hat Enterprise Linux 3 | Reporter: | Steve Dickson <steved> | ||||||||
Component: | kernel | Assignee: | Stephen Tweedie <sct> | ||||||||
Status: | CLOSED NOTABUG | QA Contact: | Brian Brock <bbrock> | ||||||||
Severity: | medium | Docs Contact: | |||||||||
Priority: | medium | ||||||||||
Version: | 3.0 | ||||||||||
Target Milestone: | --- | ||||||||||
Target Release: | --- | ||||||||||
Hardware: | All | ||||||||||
OS: | Linux | ||||||||||
Whiteboard: | |||||||||||
Fixed In Version: | Doc Type: | Bug Fix | |||||||||
Doc Text: | Story Points: | --- | |||||||||
Clone Of: | Environment: | ||||||||||
Last Closed: | 2003-08-06 16:25:54 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: | 101028 | ||||||||||
Attachments: |
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Description
Steve Dickson
2003-08-05 11:28:38 UTC
Created attachment 93399 [details]
Meminfo before the start of the testing
Created attachment 93400 [details]
Meminfo after the testing
Created attachment 93401 [details]
meminfo after the umount
There are lots of possibilities here. A leak is very very unlikely, because those tend not to get cleaned up at unmount. So one possibility is that you're not actually doing raw IO. When OraSim creates a file, the file is initially sparse (ie. no disk blocks are actually allocated, the blocks get filled in on demand.) As it writes to the file, we're filling in those holes, but O_DIRECT is disabled for such writes because of possible races: the kernel falls back to buffered writes and O_SYNC. Are you letting OraSim create the files itself, or are you preallocating the files with "dd < /dev/zero" beforehand? I was leting OraSim create the files Then that's expected behaviour. If performance is crashing as a result, then that's a VM problem which you should probably raise with Rik, as plain buffered IO shouldn't bring the system to its knees! Please try reproducing with pre-created files and reopen this bug if the problems persist. |