PORTS Forum

Ports and Interfaces => USB => Topic started by: Vinesh on April 24, 2012, 11:56:25 pm

Title: USB flash drives taking lot of time to respond to IN sometimes
Post by: Vinesh on April 24, 2012, 11:56:25 pm
I observe that after I write to flash drive of 512 bytes using Bulk only transport, and then Do several INs/Reads continuously, then after few hours the response of IN from pendrive(with data) is unusually slow, it pauses for over a second . After that it again works as expected.

Is it common for pendrives to pause for more than a second or so without responding for IN ?

This prolem occurs in many varities of flash drives.
Title: Re: USB flash drives taking lot of time to respond to IN sometimes
Post by: Jan Axelson on April 25, 2012, 10:18:58 am
I'm not aware of this. That doesn't mean it doesn't occur.

Jan
Title: Re: USB flash drives taking lot of time to respond to IN sometimes
Post by: Barry Twycross on April 25, 2012, 05:14:31 pm
It wouldn't surprise me. A flash filing system has to occasionally do housekeeping tasks (erasing old blocks etc), which can take a while.
Title: Re: USB flash drives taking lot of time to respond to IN sometimes
Post by: Bret on April 25, 2012, 06:45:18 pm
If the tests are always being done on the same computer, it's possible it's a host controller issue.  I have an older laptop that periodically receives Master Abort signals from the PCI bus hardware, which forces a hard reset of the host controller.  Of course, this forces re-enumeration of all attached devices, which usually takes a few seconds.
Title: Re: USB flash drives taking lot of time to respond to IN sometimes
Post by: Vinesh on April 26, 2012, 05:20:50 am
Barry,
How much time it takes for house keeping tasks of flash file system to be done, any pointers or idea will be helpful in this regard.
Title: Re: USB flash drives taking lot of time to respond to IN sometimes
Post by: Vinesh on April 27, 2012, 01:09:28 pm
How much time it takes for house keeping tasks of flash file system to be done ?

ANY answers/pointers will be helpful
Title: Re: USB flash drives taking lot of time to respond to IN sometimes
Post by: Bret on April 27, 2012, 02:45:04 pm
I've never seen any data on the actual times involved, but the word search I think you need to start with is Static Wear Leveling.