On Thu, 10 Aug 2006 12:22:35 +0400 Evgeniy Polyakov <[EMAIL PROTECTED]> wrote:
> On Thu, Aug 10, 2006 at 01:02:54AM -0700, Andrew Morton ([EMAIL PROTECTED]) > wrote: > > > > Afaict this mmap function gives a user a free way of getting pinned > > > > memory. > > > > What is the upper bound on the amount of memory which a user can thus > > > > obtain? > > > > > > it is limited by maximum queue length which is 4k entries right now, so > > > maximum number of paged here is 4k*40/page_size, i.e. about 40 pages on > > > x86. > > > > Is that per user or per fd? If the latter that is, with the usual > > RLIMIT_NOFILE, 160MBytes. 2GB with 64k pagesize. Problem ;) > > Per kevent fd. > I have some ideas about better mmap ring implementation, which would > dinamically grow it's buffer when events are added and reuse the same > place for next events, but there are some nitpics unresolved yet. > Let's not see there in next releases (no merge of course), until better > solution is ready. I will change that area when other things are ready. This is not a problem with the mmap interface per-se. If the proposed event code permits each user to pin 160MB of kernel memory then that would be a serious problem. - To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
