Hi all, I just tested using CONFIG_HZ_1000=y and CONFIG_HZ=1000 and as expected, this change improves the throughput. Thank you Lee for pointing that out so quickly.
Alan -- yes, I understand the ability to increase throughput by transfering more bytes and I am definitely able to see better overall throughput when increasing the number of bytes per transaction. However, I needs to still have good transaction-level timing because I cannot always queue the transactions up. Recall that each transaction is a WRITE followed by a READ. The results of the READ determine the outgoing bytes for the following transaction's WRITE. Not to sound like a broken record, but there is something seriously wrong here. This has to be a bug somewhere. It could be very well just be something as simple as issuing the right incantation with libusb, devio, etc. But, I've been using libusb for years now and am at a loss on what might have changed to require this. Any ideas??? Best regards. p.s. My apologies about the word wrap. I'm using a different mail client than my usual one and didn't realize it was not wrapping automatically. ----- Original Message ---- From: Alan Stern <[EMAIL PROTECTED]> To: Open Source <[EMAIL PROTECTED]> Cc: linux-usb-devel@lists.sourceforge.net; linux-kernel@vger.kernel.org Sent: Friday, October 13, 2006 6:56:31 AM Subject: Re: [linux-usb-devel] USB performance bug since kernel 2.6.13 (CRITICAL???) [FYI, it would make things easier for the rest of us if you can convince your email client to wrap lines before 80 columns.] I'll be interested to here if changing HZ back to 1000 makes any difference. As others have already stated, it shouldn't matter but maybe it does somehow. Even if it does, there are things you might be able to do with HZ=250 to improve throughput. You could transfer more than 512/1024 bytes per URB. You could queue multiple URBs before waiting for the first one to complete. Provided you can keep the endpoint queues filled, you should be able to achieve the maximum throughput of the hardware. Alan Stern ------------------------------------------------------------------------- Using Tomcat but need to do more? Need to support web services, security? Get stuff done quickly with pre-integrated technology to make your job easier Download IBM WebSphere Application Server v.1.0.1 based on Apache Geronimo http://sel.as-us.falkag.net/sel?cmd=lnk&kid=120709&bid=263057&dat=121642 _______________________________________________ linux-usb-devel@lists.sourceforge.net To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-devel
