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Bug 1067012 - mpt3sas / LSI SAS 9300-8i write performance bottleneck
Summary: mpt3sas / LSI SAS 9300-8i write performance bottleneck
Alias: None
Product: Fedora
Classification: Fedora
Component: kernel
Version: 19
Hardware: x86_64
OS: Linux
Target Milestone: ---
Assignee: Kernel Maintainer List
QA Contact: Fedora Extras Quality Assurance
Depends On:
TreeView+ depends on / blocked
Reported: 2014-02-19 14:06 UTC by Heinz Mauelshagen
Modified: 2014-02-19 15:42 UTC (History)
6 users (show)

Fixed In Version:
Doc Type: Bug Fix
Doc Text:
Clone Of:
Last Closed: 2014-02-19 14:31:13 UTC

Attachments (Terms of Use)

Description Heinz Mauelshagen 2014-02-19 14:06:27 UTC
Description of problem:

LSI SAS 9300-8i write performance too slow
(whilst read performance is just fine).

Version-Release number of selected component (if applicable):

Kernel 3.12.9-201.fc19.x86_64

How reproducible:

Steps to Reproduce:
1. attach 3 SSDs to adapter
2. create striped mapped device (e.g. using LVM)
3. dd of=/dev/$TheStripedDevice oflag=direct if=/dev/zero iflag=fullblock bs=2G count=1

Actual results:

Single threaded read performance is as expected, ie. 3 SSDs (3 * Samsung 840EVO  1TB) with per drive sustained read throughput of 540MB/s lead to ~1.6GB/s on a striped logical volume (all 3 attached to one SFF-8643 port of the HBA via a 1:4 mSAS to SAS cable).

Write performance on the same striped LV as in "Steps to Reproduce" (1 thread) maxes out at ~750MB/s as opposed to the maximum write throughput of ~490MB/s on each of the 3 SSDs written one by one

- ~490MB/s writing (1 thread) to the individual SSDs one by one
- ~750MB/s writing (1 thread) to all 3 SSDs in parallel via the striped LV
- ~1GB/s (3 * ~340MB/s) writing (3 threads) to all 3 SSDs in parallel;
     ie. better than the striped LV write performance

Expected results:

Expecting >1.4GB/s write maximum on the striped LV written single threaded.

Additional info:
# modinfo mpt3sas
filename:       /lib/modules/3.12.9-201.fc19.x86_64/kernel/drivers/scsi/mpt3sas/mpt3sas.ko
license:        GPL
description:    LSI MPT Fusion SAS 3.0 Device Driver
author:         LSI Corporation <>
srcversion:     FC8E3BEEAA26615A27F51C1
alias:          pci:v00001000d00000095sv*sd*bc*sc*i*
alias:          pci:v00001000d00000094sv*sd*bc*sc*i*
alias:          pci:v00001000d00000091sv*sd*bc*sc*i*
alias:          pci:v00001000d00000090sv*sd*bc*sc*i*
alias:          pci:v00001000d00000097sv*sd*bc*sc*i*
alias:          pci:v00001000d00000096sv*sd*bc*sc*i*
depends:        scsi_transport_sas,raid_class
intree:         Y
vermagic:       3.12.9-201.fc19.x86_64 SMP mod_unload 
signer:         Fedora kernel signing key
sig_key:        EE:42:35:0B:76:0C:ED:24:D6:16:92:81:FB:20:8E:24:05:25:F6:EE
sig_hashalgo:   sha256
parm:           logging_level: bits for enabling additional logging info (default=0)
parm:           max_sectors:max sectors, range 64 to 32767  default=32767 (ushort)
parm:           missing_delay: device missing delay , io missing delay (array of int)
parm:           max_lun: max lun, default=16895  (int)
parm:           diag_buffer_enable: post diag buffers (TRACE=1/SNAPSHOT=2/EXTENDED=4/default=0) (int)
parm:           disable_discovery: disable discovery  (int)
parm:           prot_mask: host protection capabilities mask, def=7  (int)
parm:           max_queue_depth: max controller queue depth  (int)
parm:           max_sgl_entries: max sg entries  (int)
parm:           msix_disable: disable msix routed interrupts (default=0) (int)
parm:           max_msix_vectors: max msix vectors - (default=8) (int)
parm:           mpt3sas_fwfault_debug: enable detection of firmware fault and halt firmware - (default=0)

Comment 1 Josh Boyer 2014-02-19 14:31:13 UTC
Please report this to the upstream kernel maintainers.  The Fedora kernel maintainers are not in a position to fix this at the moment.

Comment 2 Heinz Mauelshagen 2014-02-19 15:42:06 UTC
Filed upstream bug

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