Messages in this thread | | | From | David Mosberger <> | Date | Thu, 25 Mar 2004 20:51:54 -0800 | Subject | Re: Fw: potential /dev/urandom scalability improvement |
| |
>>>>> On Thu, 25 Mar 2004 22:19:26 -0600, Matt Mackall <mpm@selenic.com> said:
> struct entropy_store { > + /* mostly-read data: */ > + struct poolinfo poolinfo; > + __u32 *pool; > + > + /* read-write data: */ > + spinlock_t lock ____cacheline_aligned; > unsigned add_ptr; > int entropy_count; > int input_rotate; > - struct poolinfo poolinfo; > - __u32 *pool; > - spinlock_t lock; > };
Matt> Also, I think in general we'd prefer to stick the aligned bit at the Matt> front of the structure rather than at the middle, as we'll avoid extra Matt> padding. The size of cachelines is getting rather obscene on some Matt> modern processors.
Not sharing the cacheline between the mostly-read data and the read-write data is the _point_ of this change. If you reverse the order, the "poolinfo" and "pool" members will also get invalidated whenever someone updates the write-intensive data.
--david - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |