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Re: [PATCH 08/10] Don't invalidate dcache when option stack-cache is changed
- From: Yao Qi <yao at codesourcery dot com>
- To: Pedro Alves <palves at redhat dot com>
- Cc: Doug Evans <dje at google dot com>, gdb-patches <gdb-patches at sourceware dot org>
- Date: Tue, 19 Nov 2013 14:18:00 +0800
- Subject: Re: [PATCH 08/10] Don't invalidate dcache when option stack-cache is changed
- Authentication-results: sourceware.org; auth=none
- References: <1383458049-20893-1-git-send-email-yao at codesourcery dot com> <1383458049-20893-9-git-send-email-yao at codesourcery dot com> <CADPb22Q95Hfz1NOreFPwbrSnqjKQcXdYxbWc04zX1LG3MnJrYQ at mail dot gmail dot com> <528A3591 dot 2010005 at redhat dot com>
On 11/18/2013 11:43 PM, Pedro Alves wrote:
On 11/17/2013 09:44 PM, Doug Evans wrote:
I'm still not comfortable with this.
This is optimizing a rare occurrence. Users aren't expected to be
turning this on and off during a session.
My thoughts exactly. This seems to be adding extra code, therefore
a wider surface for bugs, for no apparent real use case?
The motivation of this patch is not about performance improvement, but
about using target_dcache for code caching, as I described in the mail
Nowadays, option "stack-cache" on->off and off->on transitions trigger
cache invalidation. It is not very necessary and not friendly to
using target_dcache for other purpose, such as code caching.
We've decided to use a single global target_dcache for both stack
caching and code caching. However, it is odd to me that option
"stack-cache" transitions invalidate cache for code. If the behaviour
like this is acceptable to you, I am OK to keep the existing behaviour
unchanged, and add option "code-cache". Finally, either option
"stack-cache" or option "code-cache" transitions will invalidate the
global cache. What do you think?