From: David Daney <ddaney.cavm@gmail.com>
To: "Maciej W. Rozycki" <macro@linux-mips.org>
Cc: Leonid Yegoshin <Leonid.Yegoshin@imgtec.com>,
Zenon Fortuna <zenon.fortuna@imgtec.com>,
"Steven J. Hill" <Steven.Hill@imgtec.com>,
IMG - MIPS Linux Kernel developers
<IMG-MIPSLinuxKerneldevelopers@imgtec.com>,
Linux MIPS Mailing List <linux-mips@linux-mips.org>
Subject: Re: [PATCH V2 1/3] MIPS: Fix cache flushing for swap pages with non-DMA I/O.
Date: Tue, 24 Feb 2015 14:57:57 -0800 [thread overview]
Message-ID: <54ED01F5.8040409@gmail.com> (raw)
In-Reply-To: <alpine.LFD.2.11.1502242235160.17311@eddie.linux-mips.org>
On 02/24/2015 02:50 PM, Maciej W. Rozycki wrote:
> On Tue, 24 Feb 2015, Leonid Yegoshin wrote:
>
>>> For simplicity perhaps on SMP we should just always use hit operations
>>> regardless of the size requested.
>>
>> High performance folks may not like doing a lot of stuff for 8MB VMA release
>> instead of flushing 64KB.
>
> What kind of a use case is that, what does it do?
>
>> Especially taking into account TLB exceptions and postprocessing in
>> fixup_exception() for swapped-out/not-yet-loaded-ELF blocks.
>
> The normal use for cacheflush(2) I know of is for self-modifying or other
> run-time-generated code, to synchronise caches after a block of machine
> code has been patched in -- SYNCI can also be used for that purpose these
> days,
SYNCI is only useful in non-SMP kernels.
If a thread is migrated to a different CPU between the SYNCI, and the
attempt to execute the freshly generated code, the new CPU can still
have a dirty ICACHE. So for Linux userspace, cacheflush(2) is your only
option.
David Daney
next prev parent reply other threads:[~2015-02-24 22:58 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-02-19 16:17 [PATCH V2 0/3] HIGHMEM and cache flush fixes Steven J. Hill
2015-02-19 16:17 ` Steven J. Hill
2015-02-19 16:17 ` [PATCH V2 1/3] MIPS: Fix cache flushing for swap pages with non-DMA I/O Steven J. Hill
2015-02-19 16:17 ` Steven J. Hill
2015-02-20 19:17 ` Kevin Cernekee
2015-02-24 0:56 ` Leonid Yegoshin
2015-02-24 1:13 ` Zenon Fortuna
2015-02-24 2:33 ` Maciej W. Rozycki
2015-02-24 21:06 ` Leonid Yegoshin
2015-02-24 21:51 ` Maciej W. Rozycki
2015-02-24 21:57 ` Leonid Yegoshin
2015-02-24 22:50 ` Maciej W. Rozycki
2015-02-24 22:57 ` David Daney [this message]
2015-02-24 23:19 ` Leonid Yegoshin
2015-02-24 23:58 ` David Daney
2015-02-25 0:07 ` Maciej W. Rozycki
2015-02-25 0:38 ` David Daney
2015-02-24 23:15 ` Leonid Yegoshin
2015-02-24 2:24 ` Maciej W. Rozycki
2015-02-24 16:20 ` Steven J. Hill
2015-02-19 16:17 ` [PATCH V2 2/3] MIPS: Highmem: Fixes for cache aliasing and color Steven J. Hill
2015-02-19 16:17 ` Steven J. Hill
2015-02-19 16:17 ` [PATCH V2 3/3] MIPS: Fix I-cache flushing for kmap'd pages Steven J. Hill
2015-02-19 16:17 ` Steven J. Hill
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