From: "Haitao Huang" <haitao.huang@linux.intel.com>
To: dave.hansen@linux.intel.com, tj@kernel.org, mkoutny@suse.com,
linux-kernel@vger.kernel.org, linux-sgx@vger.kernel.org,
x86@kernel.org, cgroups@vger.kernel.org, tglx@linutronix.de,
mingo@redhat.com, bp@alien8.de, hpa@zytor.com,
sohil.mehta@intel.com, tim.c.chen@linux.intel.com,
"Jarkko Sakkinen" <jarkko@kernel.org>
Cc: zhiquan1.li@intel.com, kristen@linux.intel.com,
seanjc@google.com, zhanb@microsoft.com, anakrish@microsoft.com,
mikko.ylinen@linux.intel.com, yangjie@microsoft.com,
chrisyan@microsoft.com
Subject: Re: [PATCH v9 10/15] x86/sgx: Add EPC reclamation in cgroup try_charge()
Date: Mon, 19 Feb 2024 09:12:51 -0600 [thread overview]
Message-ID: <op.2jd9vpf0wjvjmi@hhuan26-mobl.amr.corp.intel.com> (raw)
In-Reply-To: <CZ4FCQ633VLC.26Y7HUHGRSFB3@kernel.org>
On Tue, 13 Feb 2024 19:52:25 -0600, Jarkko Sakkinen <jarkko@kernel.org>
wrote:
> On Tue Feb 13, 2024 at 1:15 AM EET, Haitao Huang wrote:
>> Hi Jarkko
>>
>> On Mon, 12 Feb 2024 13:55:46 -0600, Jarkko Sakkinen <jarkko@kernel.org>
>> wrote:
>>
>> > On Mon Feb 5, 2024 at 11:06 PM EET, Haitao Huang wrote:
>> >> From: Kristen Carlson Accardi <kristen@linux.intel.com>
>> >>
>> >> When the EPC usage of a cgroup is near its limit, the cgroup needs to
>> >> reclaim pages used in the same cgroup to make room for new
>> allocations.
>> >> This is analogous to the behavior that the global reclaimer is
>> triggered
>> >> when the global usage is close to total available EPC.
>> >>
>> >> Add a Boolean parameter for sgx_epc_cgroup_try_charge() to indicate
>> >> whether synchronous reclaim is allowed or not. And trigger the
>> >> synchronous/asynchronous reclamation flow accordingly.
>> >>
>> >> Note at this point, all reclaimable EPC pages are still tracked in
>> the
>> >> global LRU and per-cgroup LRUs are empty. So no per-cgroup
>> reclamation
>> >> is activated yet.
>> >>
>> >> Co-developed-by: Sean Christopherson
>> <sean.j.christopherson@intel.com>
>> >> Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
>> >> Signed-off-by: Kristen Carlson Accardi <kristen@linux.intel.com>
>> >> Co-developed-by: Haitao Huang <haitao.huang@linux.intel.com>
>> >> Signed-off-by: Haitao Huang <haitao.huang@linux.intel.com>
>> >> ---
>> >> V7:
>> >> - Split this out from the big patch, #10 in V6. (Dave, Kai)
>> >> ---
>> >> arch/x86/kernel/cpu/sgx/epc_cgroup.c | 26 ++++++++++++++++++++++++--
>> >> arch/x86/kernel/cpu/sgx/epc_cgroup.h | 4 ++--
>> >> arch/x86/kernel/cpu/sgx/main.c | 2 +-
>> >> 3 files changed, 27 insertions(+), 5 deletions(-)
>> >>
>> >> diff --git a/arch/x86/kernel/cpu/sgx/epc_cgroup.c
>> >> b/arch/x86/kernel/cpu/sgx/epc_cgroup.c
>> >> index d399fda2b55e..abf74fdb12b4 100644
>> >> --- a/arch/x86/kernel/cpu/sgx/epc_cgroup.c
>> >> +++ b/arch/x86/kernel/cpu/sgx/epc_cgroup.c
>> >> @@ -184,13 +184,35 @@ static void
>> >> sgx_epc_cgroup_reclaim_work_func(struct work_struct *work)
>> >> /**
>> >> * sgx_epc_cgroup_try_charge() - try to charge cgroup for a single
>> EPC
>> >> page
>> >> * @epc_cg: The EPC cgroup to be charged for the page.
>> >> + * @reclaim: Whether or not synchronous reclaim is allowed
>> >> * Return:
>> >> * * %0 - If successfully charged.
>> >> * * -errno - for failures.
>> >> */
>> >> -int sgx_epc_cgroup_try_charge(struct sgx_epc_cgroup *epc_cg)
>> >> +int sgx_epc_cgroup_try_charge(struct sgx_epc_cgroup *epc_cg, bool
>> >> reclaim)
>> >> {
>> >> - return misc_cg_try_charge(MISC_CG_RES_SGX_EPC, epc_cg->cg,
>> PAGE_SIZE);
>> >> + for (;;) {
>> >> + if (!misc_cg_try_charge(MISC_CG_RES_SGX_EPC, epc_cg->cg,
>> >> + PAGE_SIZE))
>> >> + break;
>> >> +
>> >> + if (sgx_epc_cgroup_lru_empty(epc_cg->cg))
>> >> + return -ENOMEM;
>> >> + + if (signal_pending(current))
>> >> + return -ERESTARTSYS;
>> >> +
>> >> + if (!reclaim) {
>> >> + queue_work(sgx_epc_cg_wq, &epc_cg->reclaim_work);
>> >> + return -EBUSY;
>> >> + }
>> >> +
>> >> + if (!sgx_epc_cgroup_reclaim_pages(epc_cg->cg, false))
>> >> + /* All pages were too young to reclaim, try again a little later
>> */
>> >> + schedule();
>> >
>> > This will be total pain to backtrack after a while when something
>> > needs to be changed so there definitely should be inline comments
>> > addressing each branch condition.
>> >
>> > I'd rethink this as:
>> >
>> > 1. Create static __sgx_epc_cgroup_try_charge() for addressing single
>> > iteration with the new "reclaim" parameter.
>> > 2. Add a new sgx_epc_group_try_charge_reclaim() function.
>> >
>> > There's a bit of redundancy with sgx_epc_cgroup_try_charge() and
>> > sgx_epc_cgroup_try_charge_reclaim() because both have almost the
>> > same loop calling internal __sgx_epc_cgroup_try_charge() with
>> > different parameters. That is totally acceptable.
>> >
>> > Please also add my suggested-by.
>> >
>> > BR, Jarkko
>> >
>> > BR, Jarkko
>> >
>> For #2:
>> The only caller of this function, sgx_alloc_epc_page(), has the same
>> boolean which is passed into this this function.
>
> I know. This would be good opportunity to fix that up. Large patch
> sets should try to make the space for its feature best possible and
> thus also clean up the code base overally.
>
>> If we separate it into sgx_epc_cgroup_try_charge() and
>> sgx_epc_cgroup_try_charge_reclaim(), then the caller has to have the
>> if/else branches. So separation here seems not help?
>
> Of course it does. It makes the code in that location self-documenting
> and easier to remember what it does.
>
> BR, Jarkko
>
Please let me know if this aligns with your suggestion.
static int ___sgx_epc_cgroup_try_charge(struct sgx_epc_cgroup *epc_cg)
{
if (!misc_cg_try_charge(MISC_CG_RES_SGX_EPC, epc_cg->cg,
PAGE_SIZE))
return 0;
if (sgx_epc_cgroup_lru_empty(epc_cg->cg))
return -ENOMEM;
if (signal_pending(current))
return -ERESTARTSYS;
return -EBUSY;
}
/**
* sgx_epc_cgroup_try_charge() - try to charge cgroup for a single page
* @epc_cg: The EPC cgroup to be charged for the page.
*
* Try to reclaim pages in the background if the group reaches its limit
and
* there are reclaimable pages in the group.
* Return:
* * %0 - If successfully charged.
* * -errno - for failures.
*/
int sgx_epc_cgroup_try_charge(struct sgx_epc_cgroup *epc_cg)
{
int ret = ___sgx_epc_cgroup_try_charge(epc_cg);
if (ret == -EBUSY)
queue_work(sgx_epc_cg_wq, &epc_cg->reclaim_work);
return ret;
}
/**
* sgx_epc_cgroup_try_charge_reclaim() - try to charge cgroup for a single
page
* @epc_cg: The EPC cgroup to be charged for the page.
*
* Try to reclaim pages directly if the group reaches its limit and there
are
* reclaimable pages in the group.
* Return:
* * %0 - If successfully charged.
* * -errno - for failures.
*/
int sgx_epc_cgroup_try_charge_reclaim(struct sgx_epc_cgroup *epc_cg)
{
int ret;
for (;;) {
ret = ___sgx_epc_cgroup_try_charge(epc_cg);
if (ret != -EBUSY)
return ret;
if (!sgx_epc_cgroup_reclaim_pages(epc_cg->cg, current->mm))
/* All pages were too young to reclaim, try again
a little later */
schedule();
}
return 0;
}
It is a little more involved to remove the boolean for
sgx_alloc_epc_page() and its callers like sgx_encl_grow(),
sgx_alloc_va_page(). I'll send a separate patch for comments.
Thanks
Haitao
next prev parent reply other threads:[~2024-02-19 15:18 UTC|newest]
Thread overview: 106+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-02-05 21:06 [PATCH v9 00/15] Add Cgroup support for SGX EPC memory Haitao Huang
2024-02-05 21:06 ` [PATCH v9 01/15] cgroup/misc: Add per resource callbacks for CSS events Haitao Huang
2024-02-05 21:06 ` [PATCH v9 02/15] cgroup/misc: Export APIs for SGX driver Haitao Huang
2024-02-05 21:06 ` [PATCH v9 03/15] cgroup/misc: Add SGX EPC resource type Haitao Huang
2024-02-05 21:06 ` [PATCH v9 04/15] x86/sgx: Implement basic EPC misc cgroup functionality Haitao Huang
2024-02-19 12:47 ` Huang, Kai
2024-02-26 18:25 ` Michal Koutný
2024-02-27 21:35 ` Haitao Huang
2024-03-09 21:10 ` Haitao Huang
2024-02-05 21:06 ` [PATCH v9 05/15] x86/sgx: Add sgx_epc_lru_list to encapsulate LRU list Haitao Huang
2024-02-05 21:06 ` [PATCH v9 06/15] x86/sgx: Abstract tracking reclaimable pages in LRU Haitao Huang
2024-02-05 21:06 ` [PATCH v9 07/15] x86/sgx: Expose sgx_reclaim_pages() for cgroup Haitao Huang
2024-02-20 9:26 ` Huang, Kai
2024-02-05 21:06 ` [PATCH v9 08/15] x86/sgx: Implement EPC reclamation flows " Haitao Huang
2024-02-12 19:35 ` Jarkko Sakkinen
2024-02-20 9:52 ` Huang, Kai
2024-02-20 13:18 ` Michal Koutný
2024-02-20 20:09 ` Huang, Kai
2024-02-21 6:23 ` Haitao Huang
2024-02-21 10:48 ` Huang, Kai
2024-02-22 20:12 ` Haitao Huang
2024-02-22 22:24 ` Huang, Kai
2024-03-28 0:24 ` Haitao Huang
2024-02-21 6:44 ` Haitao Huang
2024-02-21 11:00 ` Huang, Kai
2024-02-22 17:20 ` Haitao Huang
2024-02-22 22:31 ` Huang, Kai
2024-02-22 18:09 ` Haitao Huang
2024-02-05 21:06 ` [PATCH v9 09/15] x86/sgx: Charge mem_cgroup for per-cgroup reclamation Haitao Huang
2024-02-12 19:46 ` Jarkko Sakkinen
2024-02-13 3:21 ` Haitao Huang
2024-02-15 23:43 ` Dave Hansen
2024-02-16 6:07 ` Haitao Huang
2024-02-16 15:15 ` Dave Hansen
2024-02-16 21:38 ` Haitao Huang
2024-02-16 21:55 ` Dave Hansen
2024-02-16 23:33 ` Haitao Huang
2024-02-05 21:06 ` [PATCH v9 10/15] x86/sgx: Add EPC reclamation in cgroup try_charge() Haitao Huang
2024-02-12 19:55 ` Jarkko Sakkinen
2024-02-12 23:15 ` Haitao Huang
2024-02-14 1:52 ` Jarkko Sakkinen
2024-02-19 15:12 ` Haitao Huang [this message]
2024-02-19 20:20 ` Jarkko Sakkinen
2024-02-19 15:39 ` [RFC PATCH] x86/sgx: Remove 'reclaim' boolean parameters Haitao Huang
2024-02-19 15:56 ` Dave Hansen
2024-02-19 20:42 ` Jarkko Sakkinen
2024-02-19 22:25 ` Haitao Huang
2024-02-19 22:43 ` Jarkko Sakkinen
2024-02-19 20:23 ` Jarkko Sakkinen
2024-02-21 11:06 ` [PATCH v9 10/15] x86/sgx: Add EPC reclamation in cgroup try_charge() Huang, Kai
2024-02-22 17:09 ` Haitao Huang
2024-02-22 21:26 ` Huang, Kai
2024-02-22 22:57 ` Haitao Huang
2024-02-23 10:18 ` Huang, Kai
2024-02-23 17:00 ` Haitao Huang
2024-02-26 1:38 ` Huang, Kai
2024-02-26 4:03 ` Haitao Huang
2024-02-26 11:36 ` Huang, Kai
2024-02-26 14:04 ` Dave Hansen
2024-02-26 21:48 ` Haitao Huang
2024-02-26 21:56 ` Dave Hansen
2024-02-26 22:34 ` Huang, Kai
2024-02-26 22:38 ` Dave Hansen
2024-02-26 22:46 ` Huang, Kai
2024-02-27 20:41 ` Jarkko Sakkinen
2024-02-27 9:26 ` Michal Koutný
2024-02-26 21:18 ` Haitao Huang
2024-02-26 22:24 ` Huang, Kai
2024-02-26 22:31 ` Dave Hansen
2024-02-26 22:38 ` Huang, Kai
2024-02-05 21:06 ` [PATCH v9 11/15] x86/sgx: Abstract check for global reclaimable pages Haitao Huang
2024-02-12 19:56 ` Jarkko Sakkinen
2024-02-21 11:34 ` Huang, Kai
2024-02-05 21:06 ` [PATCH v9 12/15] x86/sgx: Expose sgx_epc_cgroup_reclaim_pages() for global reclaimer Haitao Huang
2024-02-12 19:58 ` Jarkko Sakkinen
2024-02-21 11:10 ` Huang, Kai
2024-02-22 16:35 ` Haitao Huang
2024-02-05 21:06 ` [PATCH v9 13/15] x86/sgx: Turn on per-cgroup EPC reclamation Haitao Huang
2024-02-21 11:23 ` Huang, Kai
2024-02-22 16:36 ` Haitao Huang
2024-02-22 22:44 ` Huang, Kai
2024-02-23 18:46 ` Haitao Huang
2024-02-05 21:06 ` [PATCH v9 14/15] Docs/x86/sgx: Add description for cgroup support Haitao Huang
2024-02-05 21:06 ` [PATCH v9 15/15] selftests/sgx: Add scripts for EPC cgroup testing Haitao Huang
2024-03-27 12:55 ` Jarkko Sakkinen
2024-03-27 16:56 ` Jarkko Sakkinen
2024-03-28 0:57 ` Haitao Huang
2024-03-28 3:05 ` Haitao Huang
2024-03-30 11:23 ` Jarkko Sakkinen
2024-03-30 11:26 ` Jarkko Sakkinen
2024-04-02 11:23 ` Michal Koutný
2024-04-02 11:58 ` Jarkko Sakkinen
2024-04-02 16:20 ` Haitao Huang
2024-04-02 17:40 ` Michal Koutný
2024-04-02 18:20 ` Haitao Huang
2024-04-03 16:46 ` Jarkko Sakkinen
2024-04-03 15:33 ` Jarkko Sakkinen
2024-04-02 15:42 ` Dave Hansen
2024-04-03 15:16 ` Jarkko Sakkinen
2024-03-28 3:54 ` Haitao Huang
2024-03-30 11:15 ` Jarkko Sakkinen
2024-03-30 15:32 ` Haitao Huang
2024-03-31 16:19 ` Jarkko Sakkinen
2024-03-31 17:35 ` Haitao Huang
2024-04-01 14:10 ` Jarkko Sakkinen
2024-02-08 8:43 ` [PATCH v9 00/15] Add Cgroup support for SGX EPC memory Mikko Ylinen
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