Eric Dumazet <[EMAIL PROTECTED]> wrote: > > Most of objects returned by __cache_alloc() will be written by the caller, > (but not all callers want to write all the object, but just at the begining) > prefetchw() tells the modern CPU to think about the future writes, ie start > some memory transactions in advance.
Sounds sensible enough.. slab does try to make sure it returns the most-recently-freed object, so it's probably in cache already. But in the situation where we're allocating and using a lot of objects in succession it might help. > Some CPU lacks a prefetchw() and currently do nothing, so I ask this > question : > Should'nt make prefetchw() do at least a prefetch() ? A read hint is better > than nothing. Don't think so. I was once told that if the cacheline is in local cache for reading and the CPU decides to write to it, additional work is needed for the write so the prefetch-for-read didn't buy you anything. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
