linux_dsm_epyc7002/arch/s390/include
Heiko Carstens 1b68ac8678 s390: remove last diag 0x44 caller
diag 0x44 is a voluntary undirected yield of a virtual CPU. This has
caused a lot of performance issues in the past.

There is only one caller left, and that one is only executed if diag
0x9c (directed yield) is not present. Given that all hypervisors
implement diag 0x9c anyway, remove the last diag 0x44 to avoid that
more callers will be added.

Worst case that could happen now, if diag 0x9c is not present, is that
a virtual CPU would loop a bit instead of giving its time slice up.

diag 0x44 statistics in debugfs are kept and will always be zero, so
that user space can tell that there are no calls.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
2019-12-11 19:53:24 +01:00
..
asm s390: remove last diag 0x44 caller 2019-12-11 19:53:24 +01:00
uapi/asm arch: ipcbuf.h: make uapi asm/ipcbuf.h self-contained 2019-12-04 19:44:14 -08:00