On 09/04/2012 07:34 PM, Avi Kivity wrote: > 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(). >
Actually, not, as the loop will be very short for small sizes. -- 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 majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
