| Message ID | 20240202161554.565023-4-zi.yan@sent.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | Enable >0 order folio memory compaction | expand |
On 2/2/24 17:15, Zi Yan wrote: > From: Zi Yan <ziy@nvidia.com> > > During migration in a memory compaction, free pages are placed in an array > of page lists based on their order. But the desired free page order (i.e., > the order of a source page) might not be always present, thus leading to > migration failures and premature compaction termination. Split a high > order free pages when source migration page has a lower order to increase > migration successful rate. > > Note: merging free pages when a migration fails and a lower order free > page is returned via compaction_free() is possible, but there is too much > work. Since the free pages are not buddy pages, it is hard to identify > these free pages using existing PFN-based page merging algorithm. > > Signed-off-by: Zi Yan <ziy@nvidia.com> > --- > mm/compaction.c | 37 ++++++++++++++++++++++++++++++++++++- > 1 file changed, 36 insertions(+), 1 deletion(-) > > diff --git a/mm/compaction.c b/mm/compaction.c > index 58a4e3fb72ec..fa9993c8a389 100644 > --- a/mm/compaction.c > +++ b/mm/compaction.c > @@ -1832,9 +1832,43 @@ static struct folio *compaction_alloc(struct folio *src, unsigned long data) > struct compact_control *cc = (struct compact_control *)data; > struct folio *dst; > int order = folio_order(src); > + bool has_isolated_pages = false; > > +again: > if (!cc->freepages[order].nr_pages) { > - isolate_freepages(cc); > + int i; > + > + for (i = order + 1; i < NR_PAGE_ORDERS; i++) { You could probably just start with a loop that finds the start_order (and do the isolate_freepages() attempt if there's none) and then handle the rest outside of the loop. No need to separately handle the case where you have the exact order available? > + if (cc->freepages[i].nr_pages) { > + struct page *freepage = > + list_first_entry(&cc->freepages[i].pages, > + struct page, lru); > + > + int start_order = i; > + unsigned long size = 1 << start_order; > + > + list_del(&freepage->lru); > + cc->freepages[i].nr_pages--; > + > + while (start_order > order) { With exact order available this while loop will just be skipped and that's all the difference to it? > + start_order--; > + size >>= 1; > + > + list_add(&freepage[size].lru, > + &cc->freepages[start_order].pages); > + cc->freepages[start_order].nr_pages++; > + set_page_private(&freepage[size], start_order); > + } > + dst = (struct folio *)freepage; > + goto done; > + } > + } > + if (!has_isolated_pages) { > + isolate_freepages(cc); > + has_isolated_pages = true; > + goto again; > + } > + > if (!cc->freepages[order].nr_pages) > return NULL; > } > @@ -1842,6 +1876,7 @@ static struct folio *compaction_alloc(struct folio *src, unsigned long data) > dst = list_first_entry(&cc->freepages[order].pages, struct folio, lru); > cc->freepages[order].nr_pages--; > list_del(&dst->lru); > +done: > post_alloc_hook(&dst->page, order, __GFP_MOVABLE); > if (order) > prep_compound_page(&dst->page, order);
On 9 Feb 2024, at 13:43, Vlastimil Babka wrote: > On 2/2/24 17:15, Zi Yan wrote: >> From: Zi Yan <ziy@nvidia.com> >> >> During migration in a memory compaction, free pages are placed in an array >> of page lists based on their order. But the desired free page order (i.e., >> the order of a source page) might not be always present, thus leading to >> migration failures and premature compaction termination. Split a high >> order free pages when source migration page has a lower order to increase >> migration successful rate. >> >> Note: merging free pages when a migration fails and a lower order free >> page is returned via compaction_free() is possible, but there is too much >> work. Since the free pages are not buddy pages, it is hard to identify >> these free pages using existing PFN-based page merging algorithm. >> >> Signed-off-by: Zi Yan <ziy@nvidia.com> >> --- >> mm/compaction.c | 37 ++++++++++++++++++++++++++++++++++++- >> 1 file changed, 36 insertions(+), 1 deletion(-) >> >> diff --git a/mm/compaction.c b/mm/compaction.c >> index 58a4e3fb72ec..fa9993c8a389 100644 >> --- a/mm/compaction.c >> +++ b/mm/compaction.c >> @@ -1832,9 +1832,43 @@ static struct folio *compaction_alloc(struct folio *src, unsigned long data) >> struct compact_control *cc = (struct compact_control *)data; >> struct folio *dst; >> int order = folio_order(src); >> + bool has_isolated_pages = false; >> >> +again: >> if (!cc->freepages[order].nr_pages) { >> - isolate_freepages(cc); >> + int i; >> + >> + for (i = order + 1; i < NR_PAGE_ORDERS; i++) { > > You could probably just start with a loop that finds the start_order (and do > the isolate_freepages() attempt if there's none) and then handle the rest > outside of the loop. No need to separately handle the case where you have > the exact order available? Like this? if (list_empty(&cc->freepages[order].pages)) { int start_order; for (start_order = order + 1; start_order < NR_PAGE_ORDERS; start_order++) if (!list_empty(&cc->freepages[start_order].pages)) break; /* no free pages in the list */ if (start_order == NR_PAGE_ORDERS) { if (!has_isolated_pages) { isolate_freepages(cc); has_isolated_pages = true; goto again; } else return NULL; } struct page *freepage = list_first_entry(&cc->freepages[start_order].pages, struct page, lru); unsigned long size = 1 << start_order; list_del(&freepage->lru); while (start_order > order) { start_order--; size >>= 1; list_add(&freepage[size].lru, &cc->freepages[start_order].pages); set_page_private(&freepage[size], start_order); } dst = (struct folio *)freepage; goto done; } > >> + if (cc->freepages[i].nr_pages) { >> + struct page *freepage = >> + list_first_entry(&cc->freepages[i].pages, >> + struct page, lru); >> + >> + int start_order = i; >> + unsigned long size = 1 << start_order; >> + >> + list_del(&freepage->lru); >> + cc->freepages[i].nr_pages--; >> + >> + while (start_order > order) { > > With exact order available this while loop will just be skipped and that's > all the difference to it? > >> + start_order--; >> + size >>= 1; >> + >> + list_add(&freepage[size].lru, >> + &cc->freepages[start_order].pages); >> + cc->freepages[start_order].nr_pages++; >> + set_page_private(&freepage[size], start_order); >> + } >> + dst = (struct folio *)freepage; >> + goto done; >> + } >> + } >> + if (!has_isolated_pages) { >> + isolate_freepages(cc); >> + has_isolated_pages = true; >> + goto again; >> + } >> + >> if (!cc->freepages[order].nr_pages) >> return NULL; >> } >> @@ -1842,6 +1876,7 @@ static struct folio *compaction_alloc(struct folio *src, unsigned long data) >> dst = list_first_entry(&cc->freepages[order].pages, struct folio, lru); >> cc->freepages[order].nr_pages--; >> list_del(&dst->lru); >> +done: >> post_alloc_hook(&dst->page, order, __GFP_MOVABLE); >> if (order) >> prep_compound_page(&dst->page, order); -- Best Regards, Yan, Zi
On 2/9/24 20:57, Zi Yan wrote: > On 9 Feb 2024, at 13:43, Vlastimil Babka wrote: > >> On 2/2/24 17:15, Zi Yan wrote: >>> From: Zi Yan <ziy@nvidia.com> >>> >>> During migration in a memory compaction, free pages are placed in an array >>> of page lists based on their order. But the desired free page order (i.e., >>> the order of a source page) might not be always present, thus leading to >>> migration failures and premature compaction termination. Split a high >>> order free pages when source migration page has a lower order to increase >>> migration successful rate. >>> >>> Note: merging free pages when a migration fails and a lower order free >>> page is returned via compaction_free() is possible, but there is too much >>> work. Since the free pages are not buddy pages, it is hard to identify >>> these free pages using existing PFN-based page merging algorithm. >>> >>> Signed-off-by: Zi Yan <ziy@nvidia.com> >>> --- >>> mm/compaction.c | 37 ++++++++++++++++++++++++++++++++++++- >>> 1 file changed, 36 insertions(+), 1 deletion(-) >>> >>> diff --git a/mm/compaction.c b/mm/compaction.c >>> index 58a4e3fb72ec..fa9993c8a389 100644 >>> --- a/mm/compaction.c >>> +++ b/mm/compaction.c >>> @@ -1832,9 +1832,43 @@ static struct folio *compaction_alloc(struct folio *src, unsigned long data) >>> struct compact_control *cc = (struct compact_control *)data; >>> struct folio *dst; >>> int order = folio_order(src); >>> + bool has_isolated_pages = false; >>> >>> +again: >>> if (!cc->freepages[order].nr_pages) { >>> - isolate_freepages(cc); >>> + int i; >>> + >>> + for (i = order + 1; i < NR_PAGE_ORDERS; i++) { >> >> You could probably just start with a loop that finds the start_order (and do >> the isolate_freepages() attempt if there's none) and then handle the rest >> outside of the loop. No need to separately handle the case where you have >> the exact order available? > Like this? Almost/ > if (list_empty(&cc->freepages[order].pages)) { You don't need to do that under that if (). > int start_order; > > for (start_order = order + 1; start_order < NR_PAGE_ORDERS; Just do start_order = order; ... (not order + 1). The rest should just work. > start_order++) > if (!list_empty(&cc->freepages[start_order].pages)) > break; > > /* no free pages in the list */ > if (start_order == NR_PAGE_ORDERS) { > if (!has_isolated_pages) { > isolate_freepages(cc); > has_isolated_pages = true; > goto again; > } else > return NULL; > } > > struct page *freepage = > list_first_entry(&cc->freepages[start_order].pages, > struct page, lru); > > unsigned long size = 1 << start_order; > > list_del(&freepage->lru); > > while (start_order > order) { > start_order--; > size >>= 1; > > list_add(&freepage[size].lru, > &cc->freepages[start_order].pages); > set_page_private(&freepage[size], start_order); > } > dst = (struct folio *)freepage; > goto done; > } > >> >>> + if (cc->freepages[i].nr_pages) { >>> + struct page *freepage = >>> + list_first_entry(&cc->freepages[i].pages, >>> + struct page, lru); >>> + >>> + int start_order = i; >>> + unsigned long size = 1 << start_order; >>> + >>> + list_del(&freepage->lru); >>> + cc->freepages[i].nr_pages--; >>> + >>> + while (start_order > order) { >> >> With exact order available this while loop will just be skipped and that's >> all the difference to it? >> >>> + start_order--; >>> + size >>= 1; >>> + >>> + list_add(&freepage[size].lru, >>> + &cc->freepages[start_order].pages); >>> + cc->freepages[start_order].nr_pages++; >>> + set_page_private(&freepage[size], start_order); >>> + } >>> + dst = (struct folio *)freepage; >>> + goto done; >>> + } >>> + } >>> + if (!has_isolated_pages) { >>> + isolate_freepages(cc); >>> + has_isolated_pages = true; >>> + goto again; >>> + } >>> + >>> if (!cc->freepages[order].nr_pages) >>> return NULL; >>> } >>> @@ -1842,6 +1876,7 @@ static struct folio *compaction_alloc(struct folio *src, unsigned long data) >>> dst = list_first_entry(&cc->freepages[order].pages, struct folio, lru); >>> cc->freepages[order].nr_pages--; >>> list_del(&dst->lru); >>> +done: >>> post_alloc_hook(&dst->page, order, __GFP_MOVABLE); >>> if (order) >>> prep_compound_page(&dst->page, order); > > > -- > Best Regards, > Yan, Zi
diff --git a/mm/compaction.c b/mm/compaction.c index 58a4e3fb72ec..fa9993c8a389 100644 --- a/mm/compaction.c +++ b/mm/compaction.c @@ -1832,9 +1832,43 @@ static struct folio *compaction_alloc(struct folio *src, unsigned long data) struct compact_control *cc = (struct compact_control *)data; struct folio *dst; int order = folio_order(src); + bool has_isolated_pages = false; +again: if (!cc->freepages[order].nr_pages) { - isolate_freepages(cc); + int i; + + for (i = order + 1; i < NR_PAGE_ORDERS; i++) { + if (cc->freepages[i].nr_pages) { + struct page *freepage = + list_first_entry(&cc->freepages[i].pages, + struct page, lru); + + int start_order = i; + unsigned long size = 1 << start_order; + + list_del(&freepage->lru); + cc->freepages[i].nr_pages--; + + while (start_order > order) { + start_order--; + size >>= 1; + + list_add(&freepage[size].lru, + &cc->freepages[start_order].pages); + cc->freepages[start_order].nr_pages++; + set_page_private(&freepage[size], start_order); + } + dst = (struct folio *)freepage; + goto done; + } + } + if (!has_isolated_pages) { + isolate_freepages(cc); + has_isolated_pages = true; + goto again; + } + if (!cc->freepages[order].nr_pages) return NULL; } @@ -1842,6 +1876,7 @@ static struct folio *compaction_alloc(struct folio *src, unsigned long data) dst = list_first_entry(&cc->freepages[order].pages, struct folio, lru); cc->freepages[order].nr_pages--; list_del(&dst->lru); +done: post_alloc_hook(&dst->page, order, __GFP_MOVABLE); if (order) prep_compound_page(&dst->page, order);