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charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: 155F5140009 X-Stat-Signature: ubbrgesks17g1eudsyiewfmi1a758dmw X-HE-Tag: 1759321341-337674 X-HE-Meta: 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 pyKqWkcI Rvzph+BwIlF4NEfYQ1DiafI7OVkeMXXvUxyMxO53rMTygkMRfFLCxOB6cfXeX1aci4kpfh+soepzoijBuuiyuJjk1Zo5p5XAaqKE5Uz37ER0Ft7pN0fa26O5mizw8y8claduRcjSd9cVcWN4= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 18/09/2025 16:57, Will Deacon wrote: > On Thu, Sep 18, 2025 at 04:15:52PM +0200, Kevin Brodsky wrote: >> [...] >> >> For now, my plan is to stick to solution 3 from [2], i.e. force the >> linear map to be PTE-mapped. This is easily done on arm64 as it is the >> default, and is required for rodata=full, unless [1] is applied and the >> system supports BBML2_NOABORT. See [1] for the potential performance >> improvements we'd be missing out on (~5% ballpark). I'm not quite sure >> what the picture looks like on x86 - it may well be more significant as >> Rick suggested. > Just as a data point, but forcing the linear map down to 4k would likely > prevent us from being able to enable this on Android. We've measured a > considerable (double digit %) increase in CPU power consumption for some > real-life camera workloads when mapping the linear map at 4k granularity > thanks to the additional memory traffic from the PTW. Good to know! > At some point, KFENCE required 4k granularity for the linear map, but we > fixed it. rodata=full requires 4k granularity, but there are patches to > fix that too. So I think we should avoid making the same mistake from > the start for this series. Understood, makes sense. I'll be looking into implementing the custom PTP allocator I suggested above then. - Kevin