On 19/01/16 14:26, Boris Ostrovsky wrote: > On 01/18/2016 06:11 AM, David Vrabel wrote: >> On 15/01/16 19:43, Boris Ostrovsky wrote: >>> struct gntdev_copy_batch is over 1300 bytes in size, we shouldn't >>> put it on stack. >>> >>> Some compilers (e.g. 5.2.1) complain: >>> drivers/xen/gntdev.c: In function ‘gntdev_ioctl_grant_copy.isra.5’: >>> drivers/xen/gntdev.c:949:1: warning: the frame size of 1416 bytes >>> is larger than 1024 bytes [-Wframe-larger-than=] >> I thought I'd already reduced the size of this enough (from a batch size >> of 32 to 24) but this obviously isn't enough for 64-bit platforms. >> >> In the absence of any performance data on the best approach I would >> prefer just reducing the batch size to 16. > > That would still leave us with over 900 bytes on the stack which I think > is rather high.
The stack depth to here isn't very deep, so I think even the ~1500 byte frame was fine. > Do we expect this ioctl to be on some sort of a hot path? Yes. David _______________________________________________ Xen-devel mailing list Xen-devel@lists.xen.org http://lists.xen.org/xen-devel
