On Thu, 21 Mar 2013, Alan Stern wrote: > On Thu, 21 Mar 2013, Soeren Moch wrote: > > > Now I found out what is going on here: > > > > In itd_urb_transaction() we allocate 9 iTDs for each URB with > > number_of_packets == 64 in my case. The iTDs are added to > > sched->td_list. For a frame-aligned scheduling we need 8 iTDs, the 9th > > one is released back to the front of the streams free_list in > > iso_sched_free(). This iTD was cleared after allocation and has a frame > > number of 0 now. So for each allocation when now_frame == 0 we allocate > > from the dma_pool, not from the free_list. > > Okay, that is a problem. But it shouldn't be such a big problem, > because now_frame should not be equal to 0 very often. Oh, wait, now I get it. We never reach a steady state, because the free list never shrinks, but occasionally it does increase when now_frame is equal to 0. Even though that doesn't happen very often, the effects add up. Very good; tomorrow I will send your patch in. Alan Stern -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>