> On Mon, 22 Nov 2010 21:00:52 -0800 Michel Lespinasse <walken@xxxxxxxxxx> wrote: > > > Hi, > > > > I'd like to sollicit comments on this proposal: > > > > Currently mlock() holds mmap_sem in exclusive mode while the pages get > > faulted in. In the case of a large mlock, this can potentially take a > > very long time. > > A more compelling description of why this problem needs addressing > would help things along. Michel, as far as I know, now Michael Rubin (now I'm ccing him) are trying to make automatic MM test suit. So if possible, can you please make test case which reproduce your workload? http://code.google.com/p/samplergrapher/ I hope to join to solve your issue. and I also hope you help to understand and reproduce your issue. Thanks. > > > + /* > > + * Limit batch size to 256 pages in order to reduce > > + * mmap_sem hold time. > > + */ > > + nfault = nstart + 256 * PAGE_SIZE; > > It would be nicer if there was an rwsem API to ask if anyone is > currently blocked in down_read() or down_write(). That wouldn't be too > hard to do. It wouldn't detect people polling down_read_trylock() or > down_write_trylock() though. Andrew, yes it is certinally optimal. But I doubt it improve mlock performance a lot. because mlock is _very_ slooooooow syscall. lock regrabing may be cheap than it. So, _IF_ you can allow, I hope we take a simple method at first. personally I think Michel move forwarding right way. then I don't hope to make a hardest hurdle. Thanks. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxxx For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom policy in Canada: sign http://dissolvethecrtc.ca/ Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>