Peter Zijlstra <pet...@infradead.org> writes: > On Thu, Dec 19, 2013 at 01:17:51PM +0200, Alexander Shishkin wrote: >> Peter Zijlstra <pet...@infradead.org> writes: >> >> > On Thu, Dec 19, 2013 at 09:53:44AM +0200, Alexander Shishkin wrote: >> >> Yes and some implementations of PT have the same issue, but you can do a >> >> sufficiently large high order allocation and map it to userspace and >> >> still no copying (or parsing/decoding) in kernel space required. >> > >> > What's sufficiently large? The largest we could possibly allocate is >> > something like 4k^11 which is 8M or so. That's not all that big given >> > you keep saying it generates in the order of 100 MB/s. >> >> One chunk is 8M. You can have as many as the buddy allocator permits you >> to have. When you get a PMI, you simply switch one chunk for another and >> on the tracing goes. > > This document you referred me to looks to specify something with a > proper s/g implementation; called ToPA. There doesn't appear to be a > limit to the linked entries and you can specify a size per entry, and I > don't see anywhere why 4k would be bad.
JFYI, 11.2.4.1, "Single Output Region ToPA Implementation". Regards, -- Alex -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/