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Message-Id: <20231203193307.542794-9-yury.norov@gmail.com>
Date: Sun, 3 Dec 2023 11:32:42 -0800
From: Yury Norov <yury.norov@...il.com>
To: linux-kernel@...r.kernel.org, Fenghua Yu <fenghua.yu@...el.com>,
Dave Jiang <dave.jiang@...el.com>,
Vinod Koul <vkoul@...nel.org>, dmaengine@...r.kernel.org
Cc: Yury Norov <yury.norov@...il.com>, Jan Kara <jack@...e.cz>,
Mirsad Todorovac <mirsad.todorovac@....unizg.hr>,
Matthew Wilcox <willy@...radead.org>,
Rasmus Villemoes <linux@...musvillemoes.dk>,
Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
Maxim Kuvyrkov <maxim.kuvyrkov@...aro.org>,
Alexey Klimov <klimov.linux@...il.com>,
Bart Van Assche <bvanassche@....org>,
Sergey Shtylyov <s.shtylyov@....ru>
Subject: [PATCH v2 10/35] dmaengine: idxd: optimize perfmon_assign_event()
The function searches used_mask for a set bit in a for-loop bit by bit.
We can do it faster by using atomic find_and_set_bit().
Signed-off-by: Yury Norov <yury.norov@...il.com>
Reviewed-by: Dave Jiang <dave.jiang@...el.com>
Acked-by: Vinod Koul <vkoul@...nel.org>
---
drivers/dma/idxd/perfmon.c | 8 ++------
1 file changed, 2 insertions(+), 6 deletions(-)
diff --git a/drivers/dma/idxd/perfmon.c b/drivers/dma/idxd/perfmon.c
index fdda6d604262..4dd9c0d979c3 100644
--- a/drivers/dma/idxd/perfmon.c
+++ b/drivers/dma/idxd/perfmon.c
@@ -134,13 +134,9 @@ static void perfmon_assign_hw_event(struct idxd_pmu *idxd_pmu,
static int perfmon_assign_event(struct idxd_pmu *idxd_pmu,
struct perf_event *event)
{
- int i;
-
- for (i = 0; i < IDXD_PMU_EVENT_MAX; i++)
- if (!test_and_set_bit(i, idxd_pmu->used_mask))
- return i;
+ int i = find_and_set_bit(idxd_pmu->used_mask, IDXD_PMU_EVENT_MAX);
- return -EINVAL;
+ return i < IDXD_PMU_EVENT_MAX ? i : -EINVAL;
}
/*
--
2.40.1
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