From: Dave Hansen <dave.hansen@intel.com>
To: Haitao Huang <haitao.huang@linux.intel.com>,
linux-sgx@vger.kernel.org, Jarkko Sakkinen <jarkko@kernel.org>,
Dave Hansen <dave.hansen@linux.intel.com>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
Kristen Carlson Accardi <kristen@linux.intel.com>
Cc: linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 1/2] x86/sgx: Add accounting for tracking overcommit
Date: Tue, 11 Jan 2022 09:39:30 -0800 [thread overview]
Message-ID: <4996667d-938d-0833-f5a5-bf5ec82f69ea@intel.com> (raw)
In-Reply-To: <op.1fuaql06wjvjmi@hhuan26-mobl1.mshome.net>
On 1/11/22 08:33, Haitao Huang wrote:
> On Tue, 11 Jan 2022 09:43:35 -0600, Dave Hansen <dave.hansen@intel.com>
> wrote:
>> On 1/11/22 06:20, Haitao Huang wrote:
>>> If the system has a ton of RAM but limited EPC, I think it makes
>>> sense to allow more EPC swapping, can we do min(0.5*RAM, 2*EPC)?
>>> I suppose if the system is used for heavy enclave load, user would be
>>> willing to at least use half of RAM.
>>
>> If I have 100GB of RAM and 100MB of EPC, can I really *meaningfully*
>> run 50GB of enclaves? In that case, if everything was swapped out
>> evenly, I would only have a 499/500 chance that a given page reference
>> would fault.
>
> The formula will cap swapping at 2*EPC so only 200MB swapped out. So
> the miss is at most 1/3.
> The original hard coded cap 1.5*EPC may still consume too much RAM if
> RAM<1.5*EPC.
Oh, sorry, I read that backwards.
Basing it on the amount of RAM is a bit nasty. You might either really
overly restrict the amount of allowed EPC, or you have to handle hotplug.
next prev parent reply other threads:[~2022-01-11 17:39 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-01-07 18:16 [PATCH v2 0/2] x86/sgx: Limit EPC overcommit Kristen Carlson Accardi
2022-01-07 18:16 ` [PATCH v2 1/2] x86/sgx: Add accounting for tracking overcommit Kristen Carlson Accardi
2022-01-07 18:46 ` Dave Hansen
2022-01-07 19:16 ` Kristen Carlson Accardi
2022-01-11 14:20 ` Haitao Huang
2022-01-11 15:43 ` Dave Hansen
2022-01-11 16:33 ` Haitao Huang
2022-01-11 17:39 ` Dave Hansen [this message]
2022-01-14 17:45 ` Kristen Carlson Accardi
2022-01-08 15:59 ` Jarkko Sakkinen
2022-01-14 17:47 ` Kristen Carlson Accardi
2022-01-07 18:16 ` [PATCH v2 2/2] x86/sgx: account backing pages Kristen Carlson Accardi
2022-01-08 16:05 ` Jarkko Sakkinen
2022-01-14 17:51 ` Kristen Carlson Accardi
2022-01-14 17:55 ` Dave Hansen
2022-01-14 23:57 ` Jarkko Sakkinen
2022-01-15 0:16 ` Dave Hansen
2022-01-15 0:56 ` Jarkko Sakkinen
2022-01-14 23:52 ` Jarkko Sakkinen
2022-01-14 23:55 ` Dave Hansen
2022-01-15 0:58 ` Jarkko Sakkinen
2022-01-15 18:57 ` [PATCH v2 0/2] x86/sgx: Limit EPC overcommit Jarkko Sakkinen
2022-01-15 19:02 ` Jarkko Sakkinen
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