From: Kuan-Wei Chiu <visitorckw@gmail.com>
To: dan.j.williams@intel.com, vishal.l.verma@intel.com,
dave.jiang@intel.com, ira.weiny@intel.com
Cc: rafael@kernel.org, lenb@kernel.org, nvdimm@lists.linux.dev,
linux-acpi@vger.kernel.org, linux-kernel@vger.kernel.org,
Kuan-Wei Chiu <visitorckw@gmail.com>
Subject: [PATCH] ACPI: NFIT: Optimize nfit_mem_cmp() for efficiency
Date: Fri, 13 Oct 2023 05:59:03 +0800 [thread overview]
Message-ID: <20231012215903.2104652-1-visitorckw@gmail.com> (raw)
The original code used conditional branching in the nfit_mem_cmp
function to compare two values and return -1, 1, or 0 based on the
result. However, the list_sort comparison function only needs results
<0, >0, or =0. This patch optimizes the code to make the comparison
branchless, improving efficiency and reducing code size. This change
reduces the number of comparison operations from 1-2 to a single
subtraction operation, thereby saving the number of instructions.
Signed-off-by: Kuan-Wei Chiu <visitorckw@gmail.com>
---
drivers/acpi/nfit/core.c | 6 +-----
1 file changed, 1 insertion(+), 5 deletions(-)
diff --git a/drivers/acpi/nfit/core.c b/drivers/acpi/nfit/core.c
index f96bf32cd368..eea827d9af08 100644
--- a/drivers/acpi/nfit/core.c
+++ b/drivers/acpi/nfit/core.c
@@ -1138,11 +1138,7 @@ static int nfit_mem_cmp(void *priv, const struct list_head *_a,
handleA = __to_nfit_memdev(a)->device_handle;
handleB = __to_nfit_memdev(b)->device_handle;
- if (handleA < handleB)
- return -1;
- else if (handleA > handleB)
- return 1;
- return 0;
+ return handleA - handleB;
}
static int nfit_mem_init(struct acpi_nfit_desc *acpi_desc)
--
2.25.1
next reply other threads:[~2023-10-12 21:59 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-10-12 21:59 Kuan-Wei Chiu [this message]
2023-10-13 12:22 ` [PATCH v2] ACPI: NFIT: Optimize nfit_mem_cmp() for efficiency Kuan-Wei Chiu
2023-10-18 11:17 ` Rafael J. Wysocki
2023-10-19 4:30 ` Kuan-Wei Chiu
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