From: Qing Huang <qing.hu...@oracle.com> Date: Wed, 23 May 2018 16:22:46 -0700
> When a system is under memory presure (high usage with fragments), > the original 256KB ICM chunk allocations will likely trigger kernel > memory management to enter slow path doing memory compact/migration > ops in order to complete high order memory allocations. > > When that happens, user processes calling uverb APIs may get stuck > for more than 120s easily even though there are a lot of free pages > in smaller chunks available in the system. > > Syslog: > ... > Dec 10 09:04:51 slcc03db02 kernel: [397078.572732] INFO: task > oracle_205573_e:205573 blocked for more than 120 seconds. > ... > > With 4KB ICM chunk size on x86_64 arch, the above issue is fixed. > > However in order to support smaller ICM chunk size, we need to fix > another issue in large size kcalloc allocations. > > E.g. > Setting log_num_mtt=30 requires 1G mtt entries. With the 4KB ICM chunk > size, each ICM chunk can only hold 512 mtt entries (8 bytes for each mtt > entry). So we need a 16MB allocation for a table->icm pointer array to > hold 2M pointers which can easily cause kcalloc to fail. > > The solution is to use kvzalloc to replace kcalloc which will fall back > to vmalloc automatically if kmalloc fails. > > Signed-off-by: Qing Huang <qing.hu...@oracle.com> > Acked-by: Daniel Jurgens <dani...@mellanox.com> > Reviewed-by: Zhu Yanjun <yanjun....@oracle.com> Applied, thanks.
