he help.
- Original Message -
From: "Peter Grandi"
To: "Linux fs Btrfs"
Sent: Tuesday, 1 August, 2017 10:09:03 PM
Subject: Re: Btrfs + compression = slow performance and high cpu usage
>> [ ... ] a "RAID5 with 128KiB writes and a 768KiB stripe
>> size"
[ ... ]
> This is the "storage for beginners" version, what happens in
> practice however depends a lot on specific workload profile
> (typical read/write size and latencies and rates), caching and
> queueing algorithms in both Linux and the HA firmware.
To add a bit of slightly more advanced dis
>> [ ... ] a "RAID5 with 128KiB writes and a 768KiB stripe
>> size". [ ... ] several back-to-back 128KiB writes [ ... ] get
>> merged by the 3ware firmware only if it has a persistent
>> cache, and maybe your 3ware does not have one,
> KOS: No I don't have persistent cache. Only the 512 Mb cache
>
- Original Message -
From: "Peter Grandi"
To: "Linux fs Btrfs"
Sent: Tuesday, 1 August, 2017 3:14:07 PM
Subject: Re: Btrfs + compression = slow performance and high cpu usage
> Peter, I don't think the filefrag is showing the correct
> fragmentat
> Peter, I don't think the filefrag is showing the correct
> fragmentation status of the file when the compression is used.
As reported on a previous message the output of 'filefrag -v'
which can be used to see what is going on:
filefrag /mnt/sde3/testfile
/mnt/sde3/testfile: 49287 e
> -Original Message-
> From: linux-btrfs-ow...@vger.kernel.org [mailto:linux-btrfs-
> ow...@vger.kernel.org] On Behalf Of Konstantin V. Gavrilenko
> Sent: Tuesday, 1 August 2017 7:58 PM
> To: Peter Grandi
> Cc: Linux fs Btrfs
> Subject: Re: Btrfs + compression = slow
lance the data on the drive?
kos
- Original Message -
From: "Peter Grandi"
To: "Linux fs Btrfs"
Sent: Monday, 31 July, 2017 1:41:07 PM
Subject: Re: Btrfs + compression = slow performance and high cpu usage
[ ... ]
> grep 'model name' /proc/cpuinfo
> [ ... ] It is hard for me to see a speed issue here with
> Btrfs: for comparison I have done a simple test with a both a
> 3+1 MD RAID5 set with a 256KiB chunk size and a single block
> device on "contemporary" 1T/2TB drives, capable of sequential
> transfer rates of 150-190MB/s: [ ... ]
The fig
[ ... ]
> Also added:
Feeling very generous :-) today, adding these too:
soft# mkfs.btrfs -mraid10 -draid10 -L test5 /dev/sd{b,c,d,e}3
[ ... ]
soft# mount -t btrfs -o commit=10,compress-force=zlib /dev/sdb3 /mnt/test5
soft# rm -f /mnt/test5/testfile
soft# /usr/bin/time dd iflag=fu
[ ... ]
> grep 'model name' /proc/cpuinfo | sort -u
> model name : Intel(R) Xeon(R) CPU E5645 @ 2.40GHz
Good, contemporary CPU with all accelerations.
> The sda device is a hardware RAID5 consisting of 4x8TB drives.
[ ... ]
> Strip Size : 256 KB
So the full RMW data st
essage -
From: "Peter Grandi"
To: "Linux fs Btrfs"
Sent: Friday, 28 July, 2017 8:08:47 PM
Subject: Re: Btrfs + compression = slow performance and high cpu usage
> I am stuck with a problem of btrfs slow performance when using
> compression. [ ... ]
That to me looks l
In addition to my previous "it does not happen here" comment, if
someone is reading this thread, there are some other interesting
details:
> When the compression is turned off, I am able to get the
> maximum 500-600 mb/s write speed on this disk (raid array)
> with minimal cpu usage.
No details o
On Fri, Jul 28, 2017 at 06:20:14PM +, William Muriithi wrote:
> Hi Roman,
>
> > autodefrag
>
> This sure sounded like a good thing to enable? on paper? right?...
>
> The moment you see anything remotely weird about btrfs, this is the first
> thing you have to disable and retest without. Oh
Hi Roman,
> autodefrag
This sure sounded like a good thing to enable? on paper? right?...
The moment you see anything remotely weird about btrfs, this is the first thing
you have to disable and retest without. Oh wait, the first would be qgroups,
this one is second.
What's the problem with au
> I am stuck with a problem of btrfs slow performance when using
> compression. [ ... ]
That to me looks like an issue with speed, not performance, and
in particular with PEBCAK issues.
As to high CPU usage, when you find a way to do both compression
and checksumming without using much CPU time,
On Fri, 28 Jul 2017 17:40:50 +0100 (BST)
"Konstantin V. Gavrilenko" wrote:
> Hello list,
>
> I am stuck with a problem of btrfs slow performance when using compression.
>
> when the compress-force=lzo mount flag is enabled, the performance drops to
> 30-40 mb/s and one of the btrfs processes
Hello list,
I am stuck with a problem of btrfs slow performance when using compression.
when the compress-force=lzo mount flag is enabled, the performance drops to
30-40 mb/s and one of the btrfs processes utilises 100% cpu time.
mount options: btrfs
relatime,discard,autodefrag,compress=lzo,co
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