From: Bram Matthys <syzop@vulnscan.org>
To: linux-ide@vger.kernel.org
Subject: Write performance 50% compared to Windows
Date: Tue, 01 Nov 2016 11:37:42 +0100 [thread overview]
Message-ID: <adf65b5b8edfe0c1c99bc55a2827a68d@mail.vulnscan.org> (raw)
Hi,
I have a Samsung SSD 850 EVO 4TB and under Linux I'm only getting
~240MB/s write speed. On Windows it's 490MB/s (yes, without cache).
The read speed is the same on both Linux and Windows, though. Both are
512MB/s.
Any ideas what this could be? It can't be a slow SATA link as read
speed are fine. And since write performance is fine on Windows so I'm
kinda stunned. Not sure how to proceed / debug this any further.
I'm testing with dd if=/dev/zero of=/dev/sdX bs=1M count=65536
conv=fdatasync. Results are similar without the conv=fdatasync. On
Windows I test with AS SSD.
Prior to testing I do a ATA security erase to make sure the SSD isn't
clearing any cells during the benchmark. (Previously I used blkdiscard
but then realized this would only 'mark' the cells as unused so it might
do the actual erasing in the background)
I tested this both with a 4.4.0 and 4.8.4 Linux kernel. Another
machines (different hardware) has the same results. All have a SATA III
interface.
Dmesg:
[ 4.741663] ata2.00: ATA-9: Samsung SSD 850 EVO 4TB, EMT02B6Q, max
UDMA/133
[ 4.752974] ata1.00: ATA-9: Samsung SSD 850 EVO 4TB, EMT02B6Q, max
UDMA/133
# cat /sys/block/sda/device/queue_depth
31
If you need anything else let me know. Any help is welcomed.
Regards,
Bram
next reply other threads:[~2016-11-01 11:20 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-11-01 10:37 Bram Matthys [this message]
2016-11-01 13:03 ` Write performance 50% compared to Windows Dâniel Fraga
2016-11-02 15:07 ` Bram Matthys
[not found] ` <CAJVOszDeJSXgdMuA-f6=JDSL78SBSz+-uDNp2PX=VTjeNyz4Bg@mail.gmail.com>
2016-11-03 7:46 ` Bram Matthys
2016-11-03 14:43 ` Bram Matthys
-- strict thread matches above, loose matches on Subject: below --
2016-11-01 13:55 Bram Matthys
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