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Date: Tue, 27 Feb 2024 11:34:58 +1300
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Subject: Re: [PATCH v9 10/15] x86/sgx: Add EPC reclamation in cgroup
 try_charge()
Content-Language: en-US
To: Dave Hansen <dave.hansen@intel.com>, Haitao Huang
	<haitao.huang@linux.intel.com>, "tj@kernel.org" <tj@kernel.org>,
	"jarkko@kernel.org" <jarkko@kernel.org>, "x86@kernel.org" <x86@kernel.org>,
	"dave.hansen@linux.intel.com" <dave.hansen@linux.intel.com>,
	"cgroups@vger.kernel.org" <cgroups@vger.kernel.org>, "hpa@zytor.com"
	<hpa@zytor.com>, "mingo@redhat.com" <mingo@redhat.com>,
	"tim.c.chen@linux.intel.com" <tim.c.chen@linux.intel.com>, "mkoutny@suse.com"
	<mkoutny@suse.com>, "Mehta, Sohil" <sohil.mehta@intel.com>,
	"linux-sgx@vger.kernel.org" <linux-sgx@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"tglx@linutronix.de" <tglx@linutronix.de>, "bp@alien8.de" <bp@alien8.de>
CC: "mikko.ylinen@linux.intel.com" <mikko.ylinen@linux.intel.com>,
	"seanjc@google.com" <seanjc@google.com>, "anakrish@microsoft.com"
	<anakrish@microsoft.com>, "Zhang, Bo" <zhanb@microsoft.com>,
	"kristen@linux.intel.com" <kristen@linux.intel.com>, "yangjie@microsoft.com"
	<yangjie@microsoft.com>, "Li, Zhiquan1" <zhiquan1.li@intel.com>,
	"chrisyan@microsoft.com" <chrisyan@microsoft.com>
References: <20240205210638.157741-1-haitao.huang@linux.intel.com>
 <20240205210638.157741-11-haitao.huang@linux.intel.com>
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 <op.2jrquskiwjvjmi@hhuan26-mobl.amr.corp.intel.com>
 <3f4c6d12-7e0f-44ca-920e-ec219904e0aa@intel.com>
From: "Huang, Kai" <kai.huang@intel.com>
In-Reply-To: <3f4c6d12-7e0f-44ca-920e-ec219904e0aa@intel.com>
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> 
> Kai, I think your examples sound a little bit contrived.  Have actual
> users expressed a strong intent for doing anything with this series
> other than limiting bad actors from eating all the EPC?
I am not sure about this.  I am also trying to get a full picture.

I asked because I didn't quite like the duplicated code change in 
try_charge() in this patch and in sgx_alloc_epc_page().  I think using 
per-group reclaim we can unify the code (I have even started to write 
the code) and I don't see the downside of doing so.

So I am trying to get the actual downside of doing per-cgroup reclaim or 
the full reason that we choose global reclaim.