Daniel Henrique Barboza <danielhb...@gmail.com> writes: > On 9/20/21 10:55, Nathan Lynch wrote: >> The core DLPAR code supports two actions (add and remove) and three >> subtypes of action: >> >> * By DRC index: the action is attempted on a single specified resource. >> This is the usual case for processors. >> * By indexed count: the action is attempted on a range of resources >> beginning at the specified index. This is implemented only by the memory >> DLPAR code. >> * By count: the lower layer (CPU or memory) is responsible for locating the >> specified number of resources to which the action can be applied. >> >> I cannot find any evidence of the "by count" subtype being used by drmgr or >> qemu for processors. And when I try to exercise this code, the add case >> does not work: > > > Just to clarify: did you check both CPU and memory cases and found out that > the > 'by count' subtype isn't used with CPUs, but drmgr has some cases in which > 'by count' is used with LMBs?
Yes, drmgr uses both the 'by count' and the 'by index' methods for memory currently on PowerVM. > I'm asking because I worked with a part of the LMB removal code a few months > ago, > and got stuck in a situation in which the 'by count' and 'by indexed count' > are > similar enough to feel repetitive, but distinct enough to not be easily > reduced > into a single function. If drmgr wasn't using the 'by count' subtypes for LMBs > that would be a good chance for more code redux. The 'by count' method is definitely used for memory on PowerVM. I was under the impression that the 'by indexed count' method was used by qemu for memory sometimes; I'm pretty sure it's not used on PowerVM. >> Summary: >> >> * This code has not worked reliably since its introduction. >> * There is no evidence that it is used. >> * It contains questionable rollback behaviors in error paths which are >> difficult to test. >> >> So let's remove it. >> >> Signed-off-by: Nathan Lynch <nath...@linux.ibm.com> >> Fixes: ac71380071d1 ("powerpc/pseries: Add CPU dlpar remove functionality") >> Fixes: 90edf184b9b7 ("powerpc/pseries: Add CPU dlpar add functionality") >> Fixes: b015f6bc9547 ("powerpc/pseries: Add cpu DLPAR support for drc-info >> property") >> --- > > Tested with a QEMU pseries guest, no issues found. > > > Reviewed-by: Daniel Henrique Barboza <danielhb...@gmail.com> > Tested-by: Daniel Henrique Barboza <danielhb...@gmail.com> Thanks!