Arch Linux

JonnyRobbie

Member

Registered: 2015-04-28

Posts: 170

SD card reader has extremely slow read speed

I'm using 8GB Class-10 SDHC SanDisk rated at 40MB/s and the average read speed goes to only around 200-300 kB/s (~5MB photos/files). The write speed seems perplexingly normal. The problem's been there for quite a while, I just gotten around to do something about it. But I'm kinda stuck at what should I investigate.

$ uname -roms  
Linux 4.12.4-1-ARCH x86_64 GNU/Linux

# lspci -vs 7:00.1
07:00.1 System peripheral: JMicron Technology Corp. SD/MMC Host Controller
        Subsystem: Micro-Star International Co., Ltd. [MSI] Device 6510
        Physical Slot: 1-1
        Flags: bus master, fast devsel, latency 0, IRQ 17
        Memory at f9ffe800 (32-bit, non-prefetchable) [size=256]
        Capabilities: [a4] Power Management version 3
        Capabilities: [80] Express Endpoint, MSI 00
        Capabilities: [94] MSI: Enable- Count=1/1 Maskable- 64bit-
        Kernel driver in use: sdhci-pci
        Kernel modules: sdhci_pci

$ lsblk -fiI 179
NAME        FSTYPE LABEL     UUID                                 MOUNTPOINT
mmcblk0                                                           
`-mmcblk0p1 vfat   NIKON D90 3234-3534                            /run/media/marek/NIKON D90

$ dmesg
...
[    0.655096] mmc0: SDHCI controller on PCI [0000:07:00.1] using DMA
...
[51554.016596] mmc0: new SDHC card at address aaaa
[51554.025593] mmcblk0: mmc0:aaaa SL08G 7.40 GiB 
[51554.226681]  mmcblk0: p1
...

R00KIE

Forum Fellow

From: Between a computer and a chair

Registered: 2008-09-14

Posts: 4,734

Re: SD card reader has extremely slow read speed

Have you tried with another card from a different brand or different model? Make sure you test with recently written files.

---

R00KIE
Tm90aGluZyB0byBzZWUgaGVyZSwgbW92ZSBhbG9uZy4K

JonnyRobbie

Member

Registered: 2015-04-28

Posts: 170

Re: SD card reader has extremely slow read speed

Yes, the problem was even on my previous SD card months ago. These photos I've tested now are fairly new.

And I've tested right now with freshly copied test 130MB file. Still slow read speed.

$ mount | grep mmc
/dev/mmcblk0p1 on /run/media/marek/NIKON D90 type vfat (rw,nosuid,nodev,relatime,uid=1000,gid=1000,fmask=0022,dmask=0022,codepage=437,iocharset=iso8859-1,shortname=mixed,showexec,utf8,flush,errors=remount-ro,uhelper=udisks2)

seth

Member

Registered: 2012-09-03

Posts: 51,229

Re: SD card reader has extremely slow read speed

codepage=437,iocharset=iso8859-1,utf8

What if you format the disk with extfs?

---

How to upload text · How to boot w/o GUI · Disable Windows Fast-Start! · Fix your xinitrc

R00KIE

Forum Fellow

From: Between a computer and a chair

Registered: 2008-09-14

Posts: 4,734

Re: SD card reader has extremely slow read speed

Try this as root 'hdparm -t /dev/mmcblk0' and see what speeds you get. This does not depend on the filesystem you have installed as the card is accessed directly.

---

R00KIE
Tm90aGluZyB0byBzZWUgaGVyZSwgbW92ZSBhbG9uZy4K