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Re: LMDB write performance on Linux
- To: Howard Chu <firstname.lastname@example.org>, OpenLDAPemail@example.com
- Subject: Re: LMDB write performance on Linux
- From: Quanah Gibson-Mount <firstname.lastname@example.org>
- Date: Wed, 11 Sep 2013 10:13:22 -0700
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--On Tuesday, September 10, 2013 4:03 PM -0700 Howard Chu <email@example.com>
Quanah noted a few times in IRC that LMDB write performance was a lot
slower after upgrading from Linux 2.6.x to 3.x. I've also observed some
major slowdowns on an Ubuntu 3.5.0-23 kernel whenever the dirty page
flusher is active. Apparently this is a known issue introduced in the 3.0
I'm told that this has been fixed as of Linux 3.10. Unfortunately our
most recent round of benchmarks has all been run on our 3.5.0-23 system.
The SLAMD results we obtained for LMDB Modify throughput (tested back in
February this year) are only about 60% of the speed we expected.
I can confirm that switching to the 3.10 kernel on my ubuntu server
resolved my perf issues with slapadd and mdb on ext4. Instead of
approximately 28 hours to load my large LDIF, it now takes 66 minutes.
This brings it much more in line with ext2, which takes 59 minutes.
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