From: Karim Eshapa <karim.eshapa@gmail.com>
To: oss@buserror.net
Cc: claudiu.manoil@nxp.com, roy.pledge@nxp.com,
colin.king@canonical.com, linuxppc-dev@lists.ozlabs.org,
linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org,
Karim Eshapa <karim.eshapa@gmail.com>
Subject: [PATCH] drivers:soc:fsl:qbman:qman.c: Change a comment for an entry check inside drain_mr_fqrni function
Date: Fri, 5 May 2017 10:05:56 +0200 [thread overview]
Message-ID: <1493971556-14918-1-git-send-email-karim.eshapa@gmail.com> (raw)
Change the comment for an entry check inside function
drain_mr_fqrni() with sleep for sufficient period
of time instead of long time proccessor cycles.
Signed-off-by: Karim Eshapa <karim.eshapa@gmail.com>
---
drivers/soc/fsl/qbman/qman.c | 25 +++++++++++++------------
1 file changed, 13 insertions(+), 12 deletions(-)
diff --git a/drivers/soc/fsl/qbman/qman.c b/drivers/soc/fsl/qbman/qman.c
index 18d391e..636a7d7 100644
--- a/drivers/soc/fsl/qbman/qman.c
+++ b/drivers/soc/fsl/qbman/qman.c
@@ -1071,18 +1071,19 @@ static int drain_mr_fqrni(struct qm_portal *p)
msg = qm_mr_current(p);
if (!msg) {
/*
- * if MR was full and h/w had other FQRNI entries to produce, we
- * need to allow it time to produce those entries once the
- * existing entries are consumed. A worst-case situation
- * (fully-loaded system) means h/w sequencers may have to do 3-4
- * other things before servicing the portal's MR pump, each of
- * which (if slow) may take ~50 qman cycles (which is ~200
- * processor cycles). So rounding up and then multiplying this
- * worst-case estimate by a factor of 10, just to be
- * ultra-paranoid, goes as high as 10,000 cycles. NB, we consume
- * one entry at a time, so h/w has an opportunity to produce new
- * entries well before the ring has been fully consumed, so
- * we're being *really* paranoid here.
+ * if MR was full and h/w had other FQRNI entries to
+ * produce, we need to allow it time to produce those
+ * entries once the existing entries are consumed.
+ * A worst-case situation (fully-loaded system) means
+ * h/w sequencers may have to do 3-4 other things
+ * before servicing the portal's MR pump, each of
+ * which (if slow) may take ~50 qman cycles
+ * (which is ~200 processor cycles). So sleep with
+ * 1 ms would be very efficient, after this period
+ * we can check if there is something produced.
+ * NB, we consume one entry at a time, so h/w has
+ * an opportunity to produce new entries well before
+ * the ring has been fully consumed.
*/
msleep(1);
msg = qm_mr_current(p);
--
2.7.4
next reply other threads:[~2017-05-05 8:06 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-05-05 8:05 Karim Eshapa [this message]
2017-06-25 2:49 ` drivers:soc:fsl:qbman:qman.c: Change a comment for an entry check inside drain_mr_fqrni function Scott Wood
2017-06-25 15:02 ` karim eshapa
-- strict thread matches above, loose matches on Subject: below --
2017-05-05 8:04 [PATCH] " Karim Eshapa
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