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Starred by 2 users

Issue metadata

Status: Archived
Owner: ----
Closed: Apr 2018
EstimatedDays: ----
NextAction: ----
OS: Linux
Pri: 2
Type: Bug



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kernel samepage merging (KSM) support for up to 50 % in memory savings

Reported by d.g.jan...@gmail.com, Mar 25 2017

Issue description

UserAgent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/57.0.2987.110 Safari/537.36

Steps to reproduce the problem:
1. Try to force Chromium to use ksm with ksm-preload (https://github.com/unbrice/ksm_preload)
2. Find out there are almost no savings at all.
3. Try with uksm (https://github.com/dolohow/uksm)
4. Find out you can easily save 30-50 % of memory with many tabs and no apparent performance degradation.
5. Wonder why there wasn't even a discussion on whether chromium could advise the kernel of mergeable pages (https://www.kernel.org/doc/Documentation/vm/ksm.txt) to save significant amounts of memory.

What is the expected behavior?
int madvise(addr, length, MADV_MERGEABLE) for according pages.
viability would have to be checked with the standard kernel ksm, but I don't see why automatically detecting with uksm would be much superior to a specific solution.

What went wrong?
ksm-preloading does not advise the right pages.

Did this work before? N/A 

Chrome version: 57.0.2987.110  Channel: stable
OS Version: 
Flash Version:
 
There are important security implications with ksm: http://v.wpi.edu/wp-content/uploads/Papers/Publications/PETS2015.pdf
Labels: Needs-Triage-M57
Labels: -Needs-Triage-M57 TE-NeedsTriageHelp
This seems to out of scope from TE end, added respective label to help further investigate.
Labels: Performance-Memory
I think I've overstated the benefits. Needs more evaluation. Can't change the heading.
The benefits are really below the measuring threshold. Sorry for the incorrect report. Please close this issue as invalid.
Project Member

Comment 7 by sheriffbot@chromium.org, Apr 16 2018

Status: Archived (was: Unconfirmed)
Issue has not been modified or commented on in the last 365 days, please re-open or file a new bug if this is still an issue.

For more details visit https://www.chromium.org/issue-tracking/autotriage - Your friendly Sheriffbot

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