On Fri, 6 Mar 2009, Jens Axboe wrote: > On Thu, Mar 05 2009, Geert Uytterhoeven wrote: > > But then I noticed ps3vram_make_request() may be called concurrently, > > so I had to add a mutex to avoid data corruption. This slows the > > driver down, and in the end, the version with a thread turns out to be > > ca. 1% faster. The version without a thread is about 50 lines less > > code, though. > > That is correct, ->make_request_fn may get reentered. I'm not surprised > that performance dropped if you just shoved everything under a mutex. > You could be a little more smart and queue concurrent bio's for > processing when the current one is complete though, there are several > approaches there that be a lot faster than going all the way through the > IO stack and scheduler just to avoid concurrency.
Yes, using a spinlock and queueing requests on a list if the driver is busy can be done after 2.6.29... With kind regards, Geert Uytterhoeven Software Architect Sony Techsoft Centre Europe The Corporate Village · Da Vincilaan 7-D1 · B-1935 Zaventem · Belgium Phone: +32 (0)2 700 8453 Fax: +32 (0)2 700 8622 E-mail: geert.uytterhoe...@sonycom.com Internet: http://www.sony-europe.com/ A division of Sony Europe (Belgium) N.V. VAT BE 0413.825.160 · RPR Brussels Fortis · BIC GEBABEBB · IBAN BE41293037680010 _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@ozlabs.org https://ozlabs.org/mailman/listinfo/linuxppc-dev
