From: Paolo Bonzini <pbonzini@redhat.com>
To: Neeraj Upadhyay <quic_neeraju@quicinc.com>,
"zhangfei.gao@foxmail.com" <zhangfei.gao@foxmail.com>,
paulmck@kernel.org, zhangfei <zhangfei.gao@linaro.org>
Cc: Shameerali Kolothum Thodi <shameerali.kolothum.thodi@huawei.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"rcu@vger.kernel.org" <rcu@vger.kernel.org>,
Lai Jiangshan <jiangshanlai@gmail.com>,
Josh Triplett <josh@joshtriplett.org>,
Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
Matthew Wilcox <willy@infradead.org>,
"mtosatti@redhat.com" <mtosatti@redhat.com>,
Auger Eric <eric.auger@redhat.com>,
"chenxiang (M)" <chenxiang66@hisilicon.com>
Subject: Re: Commit 282d8998e997 (srcu: Prevent expedited GPs and blocking readers from consuming CPU) cause qemu boot slow
Date: Wed, 15 Jun 2022 12:50:14 +0200 [thread overview]
Message-ID: <7f6d9360-9254-88d6-fb34-13f248d2e542@redhat.com> (raw)
In-Reply-To: <042142db-aab2-fc4a-c1a5-371223c80440@quicinc.com>
On 6/15/22 12:40, Neeraj Upadhyay wrote:
>
> This is useful data, thanks! Did you get chance to check between 100 and
> 1000, to narrow down further, from which point (does need to be exact
> value) between 100 and 1000, you start seeing degradation at, for ex.
> 250, 500 , ...?
>
> Is it also possible to try experiment 10 and 11 with below diff.
> What I have done in below diff is, call srcu_get_delay() only once
> in try_check_zero() (and not for every loop iteration); also
> retry with a different delay for the extra iteration which is done
> when srcu_get_delay(ssp) returns 0.
>
> Once we have this data, can you also try by changing
> SRCU_RETRY_CHECK_LONG_DELAY to 100, on top of below diff.
>
> #define SRCU_RETRY_CHECK_LONG_DELAY 100
Is there any data that you would like me to gather from the KVM side,
for example with respect to how much it takes to do synchronize_srcu()
on an unpatched kernel, or the duration of the read-sides?
Thanks,
Paolo
next prev parent reply other threads:[~2022-06-15 10:50 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-06-11 16:32 Commit 282d8998e997 (srcu: Prevent expedited GPs and blocking readers from consuming CPU) cause qemu boot slow Zhangfei Gao
2022-06-11 16:59 ` Paul E. McKenney
2022-06-12 7:40 ` zhangfei.gao
2022-06-12 13:36 ` Paul E. McKenney
2022-06-12 14:59 ` zhangfei.gao
2022-06-12 16:20 ` Paul E. McKenney
2022-06-12 16:40 ` Paul E. McKenney
2022-06-12 17:29 ` Paolo Bonzini
2022-06-12 17:47 ` Paolo Bonzini
2022-06-12 18:51 ` Paul E. McKenney
2022-06-12 18:49 ` Paul E. McKenney
2022-06-12 19:23 ` Paolo Bonzini
2022-06-12 20:09 ` Paul E. McKenney
2022-06-13 3:04 ` zhangfei.gao
2022-06-13 3:57 ` Paul E. McKenney
2022-06-13 4:16 ` Paul E. McKenney
2022-06-13 6:55 ` zhangfei.gao
2022-06-13 12:18 ` Paul E. McKenney
2022-06-13 13:23 ` zhangfei.gao
2022-06-13 14:59 ` Paul E. McKenney
2022-06-13 20:55 ` Shameerali Kolothum Thodi
2022-06-14 12:19 ` Neeraj Upadhyay
2022-06-14 14:03 ` zhangfei.gao
2022-06-14 14:14 ` Neeraj Upadhyay
2022-06-14 14:57 ` zhangfei.gao
2022-06-14 14:17 ` Paul E. McKenney
2022-06-15 9:03 ` zhangfei.gao
2022-06-15 10:40 ` Neeraj Upadhyay
2022-06-15 10:50 ` Paolo Bonzini [this message]
2022-06-15 11:04 ` Neeraj Upadhyay
2022-06-18 3:07 ` zhangfei.gao
2022-06-20 7:50 ` Neeraj Upadhyay
2022-06-24 15:30 ` zhangfei.gao
2022-06-13 15:02 ` Shameerali Kolothum Thodi
2022-06-15 8:38 ` Marc Zyngier
2022-06-15 8:29 ` Marc Zyngier
2022-06-14 1:53 ` chenxiang (M)
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