linux-kernel - Re: [PATCH V2 2/4] hugetlbfs: add minimum size accounting to subpools

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Message-Id: <20150318144357.0e7e25cdca5066c39032bae6@linux-foundation.org>
Date:	Wed, 18 Mar 2015 14:43:57 -0700
From:	Andrew Morton <akpm@...ux-foundation.org>
To:	Mike Kravetz <mike.kravetz@...cle.com>
Cc:	linux-mm@...ck.org, linux-kernel@...r.kernel.org,
	Davidlohr Bueso <dave@...olabs.net>,
	Aneesh Kumar <aneesh.kumar@...ux.vnet.ibm.com>,
	Joonsoo Kim <iamjoonsoo.kim@....com>
Subject: Re: [PATCH V2 2/4] hugetlbfs: add minimum size accounting to
 subpools

On Mon, 16 Mar 2015 16:53:27 -0700 Mike Kravetz <mike.kravetz@...cle.com> wrote:

> The same routines that perform subpool maximum size accounting
> hugepage_subpool_get/put_pages() are modified to also perform
> minimum size accounting.  When a delta value is passed to these
> routines, calculate how global reservations must be adjusted
> to maintain the subpool minimum size.  The routines now return
> this global reserve count adjustment.  This global adjusted
> reserve count is then passed to the global accounting routine
> hugetlb_acct_memory().
> 

The comment layout is a bit chaotic.  Also, sentences start with
capital letters and end with little round things!  It's a bit
anal but heck, the kernel isn't written in linglish.


--- a/mm/hugetlb.c~hugetlbfs-add-minimum-size-accounting-to-subpools-fix
+++ a/mm/hugetlb.c
@@ -125,8 +125,10 @@ static long hugepage_subpool_get_pages(s
 
 	if (spool->min_hpages) {		/* minimum size accounting */
 		if (delta > spool->rsv_hpages) {
-			/* asking for more reserves than those already taken
-			 * on behalf of subpool. return difference */
+			/*
+			 * Asking for more reserves than those already taken on
+			 * behalf of subpool.  Return difference.
+			 */
 			ret = delta - spool->rsv_hpages;
 			spool->rsv_hpages = 0;
 		} else {
@@ -141,7 +143,7 @@ unlock_ret:
 }
 
 /*
- * subpool accounting for freeing and unreserving pages
+ * Subpool accounting for freeing and unreserving pages.
  * Return the number of global page reservations that must be dropped.
  * The return value may only be different than the passed value (delta)
  * in the case where a subpool minimum size must be maintained.
@@ -170,8 +172,10 @@ static long hugepage_subpool_put_pages(s
 			spool->rsv_hpages = spool->min_hpages;
 	}
 
-	/* If hugetlbfs_put_super couldn't free spool due to
-	* an outstanding quota reference, free it now. */
+	/*
+	 * If hugetlbfs_put_super couldn't free spool due to an outstanding
+	 * quota reference, free it now.
+	 */
 	unlock_or_release_subpool(spool);
 
 	return ret;
@@ -923,9 +927,9 @@ void free_huge_page(struct page *page)
 	ClearPagePrivate(page);
 
 	/*
-	 * A return code of zero implies that the subpool will be under
-	 * it's minimum size if the reservation is not restored after
-	 * page is free.  Therefore, force restore_reserve operation.
+	 * A return code of zero implies that the subpool will be under its
+	 * minimum size if the reservation is not restored after page is free.
+	 * Therefore, force restore_reserve operation.
 	 */
 	if (hugepage_subpool_put_pages(spool, 1) == 0)
 		restore_reserve = true;
@@ -2523,8 +2527,8 @@ static void hugetlb_vm_op_close(struct v
 
 	if (reserve) {
 		/*
-		 * decrement reserve counts.  The global reserve count
-		 * may be adjusted if the subpool has a minimum size.
+		 * Decrement reserve counts.  The global reserve count may be
+		 * adjusted if the subpool has a minimum size.
 		 */
 		gbl_reserve = hugepage_subpool_put_pages(spool, reserve);
 		hugetlb_acct_memory(h, -gbl_reserve);
_

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