On 08/31/2012 12:56 PM, Michael S. Tsirkin wrote: > On Fri, Aug 31, 2012 at 11:36:07AM +0200, Sasha Levin wrote: >> On 08/30/2012 03:38 PM, Michael S. Tsirkin wrote: >> >> +static unsigned int indirect_alloc_thresh = 16; >> > Why 16? Please make is MAX_SG + 1 this makes some sense. >> >> Wouldn't MAX_SG mean we always allocate from the cache? Isn't the memory waste >> too big in this case? > > Sorry. I really meant MAX_SKB_FRAGS + 1. MAX_SKB_FRAGS is 17 so gets us > threshold of 18. It is less than the size of an skb+shinfo itself so - > does it look too big to you? Also why do you think 16 is not too big but > 18 is? If there's a reason then I am fine with 16 too but then please > put it in code comment near where the value is set. > > Yes this means virtio net always allocates from cache > but this is a good thing, isn't it? Gets us more consistent > performance. kmalloc() also goes to a cache. Is there a measurable difference? Ugh, there's an ugly loop in __find_general_cachep(), which really wants to be replaced with fls(). -- error compiling committee.c: too many arguments to function -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
