From: "Emilio G. Cota" <cota@braap.org>
To: Richard Henderson <rth@twiddle.net>
Cc: "Alex Bennée" <alex.bennee@linaro.org>,
peter.maydell@linaro.org, pbonzini@redhat.com,
edgar.iglesias@xilinx.com, qemu-devel@nongnu.org,
"Peter Crosthwaite" <crosthwaite.peter@gmail.com>,
"open list:ARM" <qemu-arm@nongnu.org>
Subject: Re: [RFC DEBUG PATCH 3/3] translate-a64: fix lookup_tb_ptr hang (DEBUG!)
Date: Sun, 11 Jun 2017 01:07:30 -0400 [thread overview]
Message-ID: <20170611050730.GA12317@flamenco> (raw)
In-Reply-To: <9776b437-90b4-f2c2-4a0c-c1c6585379bf@twiddle.net>
On Sat, Jun 10, 2017 at 09:59:19 -0700, Richard Henderson wrote:
> On 06/10/2017 01:51 AM, Alex Bennée wrote:
> >I would agree with Emilio that we revert but I can't quite shake the
> >feeling we are missing an underlying problem. Would just skipping the
> >htable lookup (but keeping the tb_jmp_cache) be an OK fix for now?
>
> I agree. It seems like there's some real problem that this is uncovering.
>
> Dropping the htable lookup is certainly ok by me. If that's enough to
> un-stick your regression testing for aarch64 guest.
Unfortunately not checking the htable isn't enough to fix it for me.
I spent a few hours on Friday trying (and failing) to understand
what's going on. Regarding interrupts, I see *more* TB_EXIT_INTERRUPT
exits than without the patch, so my current best guess is that this is
a livelock kind of thing.
I'll keep digging, but regardless I think we should revert
e75449a346 ("target/aarch64: optimize indirect branches") ASAP, and
then reenable the feature ("revert the revert") once we get to the
bottom of this.
E.
WARNING: multiple messages have this Message-ID (diff)
From: "Emilio G. Cota" <cota@braap.org>
To: Richard Henderson <rth@twiddle.net>
Cc: "Alex Bennée" <alex.bennee@linaro.org>,
peter.maydell@linaro.org, pbonzini@redhat.com,
edgar.iglesias@xilinx.com, qemu-devel@nongnu.org,
"Peter Crosthwaite" <crosthwaite.peter@gmail.com>,
"open list:ARM" <qemu-arm@nongnu.org>
Subject: Re: [Qemu-devel] [RFC DEBUG PATCH 3/3] translate-a64: fix lookup_tb_ptr hang (DEBUG!)
Date: Sun, 11 Jun 2017 01:07:30 -0400 [thread overview]
Message-ID: <20170611050730.GA12317@flamenco> (raw)
In-Reply-To: <9776b437-90b4-f2c2-4a0c-c1c6585379bf@twiddle.net>
On Sat, Jun 10, 2017 at 09:59:19 -0700, Richard Henderson wrote:
> On 06/10/2017 01:51 AM, Alex Bennée wrote:
> >I would agree with Emilio that we revert but I can't quite shake the
> >feeling we are missing an underlying problem. Would just skipping the
> >htable lookup (but keeping the tb_jmp_cache) be an OK fix for now?
>
> I agree. It seems like there's some real problem that this is uncovering.
>
> Dropping the htable lookup is certainly ok by me. If that's enough to
> un-stick your regression testing for aarch64 guest.
Unfortunately not checking the htable isn't enough to fix it for me.
I spent a few hours on Friday trying (and failing) to understand
what's going on. Regarding interrupts, I see *more* TB_EXIT_INTERRUPT
exits than without the patch, so my current best guess is that this is
a livelock kind of thing.
I'll keep digging, but regardless I think we should revert
e75449a346 ("target/aarch64: optimize indirect branches") ASAP, and
then reenable the feature ("revert the revert") once we get to the
bottom of this.
E.
next prev parent reply other threads:[~2017-06-11 5:07 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-06-09 17:00 [Qemu-devel] [RFC DEBUG PATCH 0/3] debug patch for lookup-ptr hang Alex Bennée
2017-06-09 17:00 ` [Qemu-devel] [RFC DEBUG PATCH 1/3] vl: Fix broken thread=xxx option of the --accel parameter Alex Bennée
2017-06-09 17:00 ` [Qemu-devel] [RFC DEBUG PATCH 2/3] tcg-runtime: light re-factor of lookup_tb_ptr Alex Bennée
2017-06-09 17:01 ` [RFC DEBUG PATCH 3/3] translate-a64: fix lookup_tb_ptr hang (DEBUG!) Alex Bennée
2017-06-09 17:01 ` [Qemu-devel] " Alex Bennée
2017-06-10 2:29 ` Richard Henderson
2017-06-10 2:29 ` [Qemu-devel] " Richard Henderson
2017-06-10 8:51 ` Alex Bennée
2017-06-10 8:51 ` [Qemu-devel] " Alex Bennée
2017-06-10 16:59 ` Richard Henderson
2017-06-10 16:59 ` [Qemu-devel] " Richard Henderson
2017-06-11 5:07 ` Emilio G. Cota [this message]
2017-06-11 5:07 ` Emilio G. Cota
2017-06-12 10:31 ` Alex Bennée
2017-06-12 10:31 ` [Qemu-devel] " Alex Bennée
2017-06-13 22:53 ` [PATCH] target/aarch64: exit to main loop after handling MSR Emilio G. Cota
2017-06-13 22:53 ` [Qemu-devel] " Emilio G. Cota
2017-06-13 23:01 ` no-reply
2017-06-14 4:48 ` Richard Henderson
2017-06-14 4:48 ` [Qemu-devel] " Richard Henderson
2017-06-14 10:46 ` Paolo Bonzini
2017-06-14 10:46 ` [Qemu-devel] " Paolo Bonzini
2017-06-14 11:45 ` Alex Bennée
2017-06-14 11:45 ` [Qemu-devel] " Alex Bennée
2017-06-14 12:02 ` Paolo Bonzini
2017-06-14 12:02 ` [Qemu-devel] " Paolo Bonzini
2017-06-14 12:14 ` Alex Bennée
2017-06-14 12:14 ` [Qemu-devel] " Alex Bennée
2017-06-14 12:16 ` Paolo Bonzini
2017-06-14 12:16 ` [Qemu-devel] " Paolo Bonzini
2017-06-14 12:35 ` Alex Bennée
2017-06-14 12:35 ` [Qemu-devel] " Alex Bennée
2017-06-14 12:43 ` Paolo Bonzini
2017-06-14 12:43 ` [Qemu-devel] " Paolo Bonzini
2017-06-14 10:38 ` Alex Bennée
2017-06-14 10:38 ` [Qemu-devel] " Alex Bennée
2017-06-09 21:11 ` [Qemu-devel] [RFC DEBUG PATCH 0/3] debug patch for lookup-ptr hang no-reply
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