From: Leonid Yegoshin <Leonid.Yegoshin@imgtec.com>
To: <yhb@ruijie.com.cn>, <ralf@linux-mips.org>
Cc: <linux-mips@linux-mips.org>
Subject: Re: MIPS: We need to clear MMU contexts of all other processes when asid_cache(cpu) wraps to 0.
Date: Mon, 11 Jul 2016 11:02:00 -0700 [thread overview]
Message-ID: <5783DF18.1080408@imgtec.com> (raw)
In-Reply-To: <80B78A8B8FEE6145A87579E8435D78C30205D5F3@fzex.ruijie.com.cn>
On 07/10/2016 06:04 AM, yhb@ruijie.com.cn wrote:
> Subject: [PATCH] MIPS: We need to clear MMU contexts of all other processes
> when asid_cache(cpu) wraps to 0.
>
> Suppose that asid_cache(cpu) wraps to 0 every n days.
> case 1:
> (1)Process 1 got ASID 0x101.
> (2)Process 1 slept for n days.
> (3)asid_cache(cpu) wrapped to 0x101, and process 2 got ASID 0x101.
> (4)Process 1 is woken,and ASID of process 1 is same as ASID of process 2.
>
> case 2:
> (1)Process 1 got ASID 0x101 on CPU 1.
> (2)Process 1 migrated to CPU 2.
> (3)Process 1 migrated to CPU 1 after n days.
> (4)asid_cache on CPU 1 wrapped to 0x101, and process 2 got ASID 0x101.
> (5)Process 1 is scheduled, and ASID of process 1 is same as ASID of process 2.
>
> So we need to clear MMU contexts of all other processes when asid_cache(cpu) wraps to 0.
>
> Signed-off-by: yhb <yhb@ruijie.com.cn>
>
I think a more clear description should be given here - there is no
indication that wrap happens over 32bit integer.
And taking into account "n days" frequency - can we just kill all local
ASIDs in all processes (additionally to local_flush_tlb_all) and enforce
reassignment if wrap happens? It should be a very rare event, you are
first to hit this.
It seems to be some localized stuff in get_new_mmu_context() instead of
widespread patching.
- Leonid.
WARNING: multiple messages have this Message-ID (diff)
From: Leonid Yegoshin <Leonid.Yegoshin@imgtec.com>
To: yhb@ruijie.com.cn, ralf@linux-mips.org
Cc: linux-mips@linux-mips.org
Subject: Re: MIPS: We need to clear MMU contexts of all other processes when asid_cache(cpu) wraps to 0.
Date: Mon, 11 Jul 2016 11:02:00 -0700 [thread overview]
Message-ID: <5783DF18.1080408@imgtec.com> (raw)
Message-ID: <20160711180200.Aw2v2q_G98jswDLhEzWD0Kl9uKfpvWm2H7Nuhnp6QNI@z> (raw)
In-Reply-To: <80B78A8B8FEE6145A87579E8435D78C30205D5F3@fzex.ruijie.com.cn>
On 07/10/2016 06:04 AM, yhb@ruijie.com.cn wrote:
> Subject: [PATCH] MIPS: We need to clear MMU contexts of all other processes
> when asid_cache(cpu) wraps to 0.
>
> Suppose that asid_cache(cpu) wraps to 0 every n days.
> case 1:
> (1)Process 1 got ASID 0x101.
> (2)Process 1 slept for n days.
> (3)asid_cache(cpu) wrapped to 0x101, and process 2 got ASID 0x101.
> (4)Process 1 is woken,and ASID of process 1 is same as ASID of process 2.
>
> case 2:
> (1)Process 1 got ASID 0x101 on CPU 1.
> (2)Process 1 migrated to CPU 2.
> (3)Process 1 migrated to CPU 1 after n days.
> (4)asid_cache on CPU 1 wrapped to 0x101, and process 2 got ASID 0x101.
> (5)Process 1 is scheduled, and ASID of process 1 is same as ASID of process 2.
>
> So we need to clear MMU contexts of all other processes when asid_cache(cpu) wraps to 0.
>
> Signed-off-by: yhb <yhb@ruijie.com.cn>
>
I think a more clear description should be given here - there is no
indication that wrap happens over 32bit integer.
And taking into account "n days" frequency - can we just kill all local
ASIDs in all processes (additionally to local_flush_tlb_all) and enforce
reassignment if wrap happens? It should be a very rare event, you are
first to hit this.
It seems to be some localized stuff in get_new_mmu_context() instead of
widespread patching.
- Leonid.
next prev parent reply other threads:[~2016-07-11 18:02 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-07-10 13:04 MIPS: We need to clear MMU contexts of all other processes when asid_cache(cpu) wraps to 0 yhb
2016-07-10 13:04 ` yhb
2016-07-11 9:30 ` James Hogan
2016-07-11 9:30 ` James Hogan
2016-07-11 18:02 ` Leonid Yegoshin [this message]
2016-07-11 18:02 ` Leonid Yegoshin
2016-07-11 18:05 ` [PATCH] " Leonid Yegoshin
2016-07-11 18:05 ` Leonid Yegoshin
2016-07-11 18:07 ` James Hogan
2016-07-11 18:07 ` James Hogan
2016-07-11 18:19 ` [PATCH] " Leonid Yegoshin
2016-07-11 18:19 ` Leonid Yegoshin
2016-07-11 19:21 ` James Hogan
2016-07-11 19:21 ` James Hogan
2016-07-11 19:39 ` Leonid Yegoshin
2016-07-11 19:39 ` Leonid Yegoshin
2016-07-11 20:18 ` James Hogan
2016-07-11 20:18 ` James Hogan
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