Nathan Lynch [off-list ref] writes:

Michael Ellerman [off-list ref] writes:

quoted

One thought, which I possibly should not put in writing, is that we
could use the alignment of the pointer as a poor man's substitute for a
counter, eg:

+static inline struct drmem_lmb *drmem_lmb_next(struct drmem_lmb *lmb)
+{
+	if (lmb % PAGE_SIZE == 0)
+		cond_resched();
+
+	return ++lmb;
+}

I think the lmbs are allocated in a block, so I think that will work.
Maybe PAGE_SIZE is not the right size to use, but you get the idea.

Gross I know, but might be OK as short term solution?

OK, looking into this.

To follow up:

I wasn't able to measure more than ~1% difference in DLPAR memory
performance with my original version of this, but that was on a
relatively small configuration - hundreds of elements in the array as
opposed to thousands. I took an educated guess at an appropriate
interval and posted v2:

https://lore.kernel.org/linuxppc-dev/20200812012005.1919255-1-nathanl@linux.ibm.com/ (local)