Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::3:7 as permitted sender) client-ip=2620:137:e000::3:7;
From:   Alexandru Elisei <alexandru.elisei@arm.com>
To:     catalin.marinas@arm.com, will@kernel.org, oliver.upton@linux.dev,
        maz@kernel.org, james.morse@arm.com, suzuki.poulose@arm.com,
        yuzenghui@huawei.com, arnd@arndb.de, akpm@linux-foundation.org,
        mingo@redhat.com, peterz@infradead.org, juri.lelli@redhat.com,
        vincent.guittot@linaro.org, dietmar.eggemann@arm.com,
        rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de,
        bristot@redhat.com, vschneid@redhat.com, mhiramat@kernel.org,
        rppt@kernel.org, hughd@google.com
Cc:     pcc@google.com, steven.price@arm.com, anshuman.khandual@arm.com,
        vincenzo.frascino@arm.com, david@redhat.com, eugenis@google.com,
        kcc@google.com, hyesoo.yu@samsung.com,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org,
        kvmarm@lists.linux.dev, linux-fsdevel@vger.kernel.org,
        linux-arch@vger.kernel.org, linux-mm@kvack.org,
        linux-trace-kernel@vger.kernel.org
Subject: [PATCH RFC v2 03/27] mm: cma: Make CMA_ALLOC_SUCCESS/FAIL count the number of pages
Date:   Sun, 19 Nov 2023 16:56:57 +0000
Message-Id: <20231119165721.9849-4-alexandru.elisei@arm.com>
In-Reply-To: <20231119165721.9849-1-alexandru.elisei@arm.com>
References: <20231119165721.9849-1-alexandru.elisei@arm.com>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

The CMA_ALLOC_SUCCESS, respectively CMA_ALLOC_FAIL, are increased by one
after each cma_alloc() function call. This is done even though cma_alloc()
can allocate an arbitrary number of CMA pages. When looking at
/proc/vmstat, the number of successful (or failed) cma_alloc() calls
doesn't tell much with regards to how many CMA pages were allocated via
cma_alloc() versus via the page allocator (regular allocation request or
PCP lists refill).

This can also be rather confusing to a user who isn't familiar with the
code, since the unit of measurement for nr_free_cma is the number of pages,
but cma_alloc_success and cma_alloc_fail count the number of cma_alloc()
function calls.

Let's make this consistent, and arguably more useful, by having
CMA_ALLOC_SUCCESS count the number of successfully allocated CMA pages, and
CMA_ALLOC_FAIL count the number of pages cma_alloc() failed to allocate.

For users that wish to track the number of cma_alloc() calls, there are
tracepoints for that already implemented.

Signed-off-by: Alexandru Elisei <alexandru.elisei@arm.com>
---
 mm/cma.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/mm/cma.c b/mm/cma.c
index 2b2494fd6b59..2b74db5116d5 100644
--- a/mm/cma.c
+++ b/mm/cma.c
@@ -517,10 +517,10 @@ struct page *cma_alloc(struct cma *cma, unsigned long count,
 	pr_debug("%s(): returned %p\n", __func__, page);
 out:
 	if (page) {
-		count_vm_event(CMA_ALLOC_SUCCESS);
+		count_vm_events(CMA_ALLOC_SUCCESS, count);
 		cma_sysfs_account_success_pages(cma, count);
 	} else {
-		count_vm_event(CMA_ALLOC_FAIL);
+		count_vm_events(CMA_ALLOC_FAIL, count);
 		if (cma)
 			cma_sysfs_account_fail_pages(cma, count);
 	}
-- 
2.42.1