linux-kernel - [PATCH 1/2] soc: fsl: dpio: Add prefetch instruction

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Message-ID: <1544803440-32755-1-git-send-email-ruxandra.radulescu@nxp.com>
Date:   Fri, 14 Dec 2018 16:04:05 +0000
From:   Ioana Ciocoi Radulescu <ruxandra.radulescu@....com>
To:     Leo Li <leoyang.li@....com>, Roy Pledge <roy.pledge@....com>
CC:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        Ioana Ciornei <ioana.ciornei@....com>
Subject: [PATCH 1/2] soc: fsl: dpio: Add prefetch instruction

In dpaa2_io_store_next(), if the current dequeue entry is not
the last, prefetch the next one as most likely it will be
requested shortly by the consumer driver.

This brings a ~3% improvement for dpaa2 ethernet driver
IP forwarding with small size frames.

Signed-off-by: Ioana Radulescu <ruxandra.radulescu@....com>
---
 drivers/soc/fsl/dpio/dpio-service.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/soc/fsl/dpio/dpio-service.c b/drivers/soc/fsl/dpio/dpio-service.c
index 5583d28..56a35c0 100644
--- a/drivers/soc/fsl/dpio/dpio-service.c
+++ b/drivers/soc/fsl/dpio/dpio-service.c
@@ -613,6 +613,7 @@ struct dpaa2_dq *dpaa2_io_store_next(struct dpaa2_io_store *s, int *is_last)
 		if (!(dpaa2_dq_flags(ret) & DPAA2_DQ_STAT_VALIDFRAME))
 			ret = NULL;
 	} else {
+		prefetch(&s->vaddr[s->idx]);
 		*is_last = 0;
 	}
 
-- 
2.7.4