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    SubjectRe: [PATCH v3 2/2] virtio-ring: Allocate indirect buffers from cache when possible
    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.



    --
    MST


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