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Re: [Qemu-devel] [RFC]Two ideas to optimize updating irq routing table
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From: |
Christian Borntraeger |
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Subject: |
Re: [Qemu-devel] [RFC]Two ideas to optimize updating irq routing table |
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Date: |
Wed, 26 Mar 2014 12:14:34 +0100 |
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User-agent: |
Mozilla/5.0 (X11; Linux i686; rv:24.0) Gecko/20100101 Thunderbird/24.4.0 |
On 26/03/14 09:22, Gonglei (Arei) wrote:
> Without patches, ping time can jump from 0.3ms to 2ms-30ms. With
> synchronize_srcu
> patch, ping time is worse. With synchronize_srcu_expedited patch, ping time
> is
> overall good, though sometimes ping time jump to 1ms-3ms.
Just to understand whats going on, does something like
diff --git a/kernel/rcu/srcu.c b/kernel/rcu/srcu.c
index 3318d82..432c2a2 100644
--- a/kernel/rcu/srcu.c
+++ b/kernel/rcu/srcu.c
@@ -331,7 +331,7 @@ EXPORT_SYMBOL_GPL(__srcu_read_unlock);
*/
#define SRCU_RETRY_CHECK_DELAY 5
#define SYNCHRONIZE_SRCU_TRYCOUNT 2
-#define SYNCHRONIZE_SRCU_EXP_TRYCOUNT 12
+#define SYNCHRONIZE_SRCU_EXP_TRYCOUNT 50
/*
* @@@ Wait until all pre-existing readers complete. Such readers
make the problem go away?