On Fri 2016-08-05 20:17:36, PINTU KUMAR wrote: > Hi, > > On Fri, Aug 05, 2016 at 10:26:37AM +0530, PINTU KUMAR wrote: > > > Hi All, > > > > > > For one of our ARM embedded product, we recently updated the Kernel > > > version from > > > 3.4 to 3.18 and we noticed that the same application memory usage (PSS > > > value) gone up by ~10% and for some cases it even crossed ~50%. > > > There is no change in platform part. All platform component was built > > > with ARM 32-bit toolchain. > > > However, the Kernel is changed from 32-bit to 64-bit. > > > > > > Is upgrading Kernel version and moving from 32-bit to 64-bit is such a risk > ? > > > After the upgrade, what can we do further to reduce the application > > > memory usage ? > > > Is there any other factor that will help us to improve without major > > > modifications in platform ? > > > > > > As a proof, we did a small experiment on our Ubuntu-32 bit machine. > > > We upgraded Ubuntu Kernel version from 3.13 to 4.01 and we observed > > > the > > > following: > > > ---------------------------------------------------------------------- > > > ---------- > > > ------------- > > > |UBUNTU-32 bit |Kernel 3.13 |Kernel 4.03 |DIFF | > > > |CALCULATOR PSS |6057 KB |6466 KB |409 KB | > > > ---------------------------------------------------------------------- > > > ---------- > > > ------------- > > > So, just by upgrading the Kernel version: PSS value for calculator is > > > increased by 409KB. > > > > > > If anybody knows any in-sight about it please point out more details > > > about the root cause. > > > > One of culprit is [8c6e50b0290c, mm: introduce vm_ops->map_pages()]. > Ok. Thank you for your reply. > So, if I revert this patch, will the memory usage be decreased for the processes > with Kernel 3.18 ? I guess you should try it... You may want to try the same kernel version, once in 32-bit and once in 64-bit version. And you may consider moving to recent kernel. Yes, 64-bit kernel will increase memory usage _of kernel_, but... Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>