[gpfsug-discuss] mmap performance against Spectrum Scale

Bryan Banister bbanister at jumptrading.com
Fri Jan 12 16:12:13 GMT 2018


You could put all of your data onto SSDs in a RAID1 configuration so that you don’t have insane read-modify-write penalties on writes (RAID1) and avoid horrible seek thrashing that spinning rust requires (SSD random access medium) for your 4K I/O operations.

One of my favorite Yuri quotes, “The mmap code is like asbestos… best not to touch it”.  He gave many reasons why mmap operations on a distributed file system is incredibly hard and not recommended.
-Bryan

From: gpfsug-discuss-bounces at spectrumscale.org [mailto:gpfsug-discuss-bounces at spectrumscale.org] On Behalf Of Sven Oehme
Sent: Friday, January 12, 2018 8:45 AM
To: coetzee.ray at gmail.com; gpfsug main discussion list <gpfsug-discuss at spectrumscale.org>
Subject: Re: [gpfsug-discuss] mmap performance against Spectrum Scale

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what version of Scale are you using right now ?

On Fri, Jan 12, 2018 at 2:29 AM Ray Coetzee <coetzee.ray at gmail.com<mailto:coetzee.ray at gmail.com>> wrote:
I'd like to ask the group of their experiences in improving the performance of applications that use mmap calls against files on Spectrum Scale.

Besides using an NFS export from CES instead of a native GPFS mount, or precaching the dataset into the pagepool, what other approaches are there to offset the performance hit of the 4K IO size?

Kind regards

Ray Coetzee
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