Kunkun, On Fri, Mar 05, 2021 at 03:50:34PM +0800, Kunkun Jiang wrote: > When the host page is a huge page and something is sent in the > current iteration, the migration_rate_limit() should be executed. > If not, this function can be omitted to save time. > > Rename tmppages to pages_this_iteration to express its meaning > more clearly. > > Signed-off-by: Keqian Zhu <zhukeqi...@huawei.com> > Signed-off-by: Kunkun Jiang <jiangkun...@huawei.com> > --- > migration/ram.c | 21 ++++++++++++++------- > 1 file changed, 14 insertions(+), 7 deletions(-) > > diff --git a/migration/ram.c b/migration/ram.c > index a168da5cdd..9fc5b2997c 100644 > --- a/migration/ram.c > +++ b/migration/ram.c > @@ -1988,7 +1988,7 @@ static int ram_save_target_page(RAMState *rs, > PageSearchStatus *pss, > static int ram_save_host_page(RAMState *rs, PageSearchStatus *pss, > bool last_stage) > { > - int tmppages, pages = 0; > + int pages = 0; > size_t pagesize_bits = > qemu_ram_pagesize(pss->block) >> TARGET_PAGE_BITS; > unsigned long start_page = pss->page; > @@ -2000,21 +2000,28 @@ static int ram_save_host_page(RAMState *rs, > PageSearchStatus *pss, > } > > do { > + int pages_this_iteration = 0; > + > /* Check if the page is dirty and send it if it is */ > if (!migration_bitmap_clear_dirty(rs, pss->block, pss->page)) { > pss->page++; > continue; > } > > - tmppages = ram_save_target_page(rs, pss, last_stage); > - if (tmppages < 0) { > - return tmppages; > + pages_this_iteration = ram_save_target_page(rs, pss, last_stage); > + if (pages_this_iteration < 0) { > + return pages_this_iteration; > } > > - pages += tmppages; > + pages += pages_this_iteration;
To me, both names are okay, it's just that the new name doesn't really provide a lot more new information, while it's even longer... Since you seem to prefer cleaning up tmppages, I'm actually thinking whether it should be called as "pages" at all since ram_save_target_page() majorly only returns either 1 if succeeded or <0 if error. There's only one very corner case of xbzrle where it can return 0 in save_xbzrle_page(): if (encoded_len == 0) { trace_save_xbzrle_page_skipping(); return 0; } I think it means the page didn't change at all, then I'm also wondering maybe it can also return 1 showing one page migrated (though actually skipped!) which should still be fine for the callers, e.g., ram_find_and_save_block() who will finally check this "pages" value. So I think _maybe_ that's a nicer cleanup to change that "return 0" to "return 1", then another patch to make the return value to be (1) return 0 if page saved, or (2) return <0 if error. Then here in ram_save_host_page() tmppages can be renamed to "ret" or "succeed". > pss->page++; > - /* Allow rate limiting to happen in the middle of huge pages */ > - migration_rate_limit(); > + /* > + * Allow rate limiting to happen in the middle of huge pages if > + * something is sent in the current iteration. > + */ > + if (pagesize_bits > 1 && pages_this_iteration > 0) { > + migration_rate_limit(); > + } I don't know whether this matters either.. Two calls in there: migration_update_counters(s, now); qemu_file_rate_limit(s->to_dst_file); migration_update_counters() is mostly a noop for 99.9% cases. Looks still okay... Thanks, > } while ((pss->page & (pagesize_bits - 1)) && > offset_in_ramblock(pss->block, > ((ram_addr_t)pss->page) << > TARGET_PAGE_BITS)); > -- > 2.23.0 > -- Peter Xu