On Thu, 2009-11-05 at 09:18 -0600, Steve Gunther wrote: > I am modifying my ivtv settings to increase buffer size. I am using > the following string; > > options ivtv enc_yuv_buffers=8 enc_mpg_buffers=48 enc_vbi_buffers=16 > enc_pcm_buffers=960 > > So by my math 8MB YUV + 48M MPG + 16M VBI + 960k = ~73M per tuner. > > I have four tuners... > > After boot I; > > sudo rmmod ivtv > > My memory usage is at 435672k used. After I; > > sudo modprobe ivtv > > My memory usage is 1029156k used, for a difference of 593484k or ~148M > per card. > > > As far as the modino states the defaults should be So by my math 2MB > YUV + 4M MPG + 1M VBI + 320k = ~7M per tuner. > > With no modifier string my memory usage is 16M per card. > > Any idea why my memory usage would be approximately double the > assigned buffer size?
Likely because you don't have a hardware IOMMU, and thus the linux kernel is using it's "software" IO MMU and allocating DMA bounce buffers. That's just a guess of course. If you are upping the memory for buffers because you are worried that you CPU can't keep up, be aware that I believe software bounce buffers require the CPU to do memcpy()'s of the contents of the buffers to get them to the ivtv driver. Regards, Andy > -Steve _______________________________________________ ivtv-users mailing list [email protected] http://ivtvdriver.org/mailman/listinfo/ivtv-users
