Hi Kai
On Mon, 24 Jul 2023 05:04:48 -0500, Huang, Kai <kai.huang@xxxxxxxxx> wrote:
On Mon, 2023-07-17 at 08:23 -0500, Haitao Huang wrote:
On Mon, 17 Jul 2023 07:45:36 -0500, Jarkko Sakkinen <jarkko@xxxxxxxxxx>
wrote:
> On Wed Jul 12, 2023 at 11:01 PM UTC, Haitao Huang wrote:
> > From: Kristen Carlson Accardi <kristen@xxxxxxxxxxxxxxx>
> >
> > Introduce a data structure to wrap the existing reclaimable list
> > and its spinlock in a struct to minimize the code changes needed
> > to handle multiple LRUs as well as reclaimable and non-reclaimable
> > lists. The new structure will be used in a following set of patches
to
> > implement SGX EPC cgroups.
Although briefly mentioned in the first patch, it would be better to put
more
background about the "reclaimable" and "non-reclaimable" thing here,
focusing on
_why_ we need multiple LRUs (presumably you mean two lists: reclaimable
and non-
reclaimable).
Sure I can add a little more background to introduce the
reclaimable/unreclaimable concept. But why we need multiple LRUs would be
self-evident in later patches, not sure I will add details here.
> >
> > The changes to the structure needed for unreclaimable lists will be
> > added in later patches.
> >
> > Signed-off-by: Sean Christopherson <sean.j.christopherson@xxxxxxxxx>
> > Signed-off-by: Kristen Carlson Accardi <kristen@xxxxxxxxxxxxxxx>
> > Signed-off-by: Haitao Huang <haitao.huang@xxxxxxxxxxxxxxx>
> > Cc: Sean Christopherson <seanjc@xxxxxxxxxx>
> >
> > V3:
> > Removed the helper functions and revised commit messages
Please put change history into:
---
change history
---
So it can be stripped away when applying the patch.
Will do that.
> > ---
> > arch/x86/kernel/cpu/sgx/sgx.h | 17 +++++++++++++++++
> > 1 file changed, 17 insertions(+)
> >
> > diff --git a/arch/x86/kernel/cpu/sgx/sgx.h
> > b/arch/x86/kernel/cpu/sgx/sgx.h
> > index f6e3c5810eef..77fceba73a25 100644
> > --- a/arch/x86/kernel/cpu/sgx/sgx.h
> > +++ b/arch/x86/kernel/cpu/sgx/sgx.h
> > @@ -92,6 +92,23 @@ static inline void *sgx_get_epc_virt_addr(struct
> > sgx_epc_page *page)
> > return section->virt_addr + index * PAGE_SIZE;
> > }
> >
> > +/*
> > + * This data structure wraps a list of reclaimable EPC pages, and a
> > list of
> > + * non-reclaimable EPC pages and is used to implement a LRU policy
> > during
> > + * reclamation.
> > + */
I'd prefer to not mention the "non-reclaimable" thing in this patch, but
defer
to the one actually introduces the "non-reclaimable" list. Actually, I
don't
think we even need this comment, given you have this in the structure:
struct list_head reclaimable;
Agreed.
Which already explains the "reclaimable" list. I suppose the
non-reclaimable
list would be named similarly thus need no comment either.
Also, I am wondering why you need to split this out as a separate
patch. It
basically does nothing. To me you should just merge this to the next
patch,
I think Kristen splitted the original patch based on Dave's comments:
https://lore.kernel.org/all/e71d76b2-4368-4627-abd4-2163e6786a20@xxxxxxxxx/
which actually does what you claimed in the changelog:
Introduce a data structure to wrap the existing reclaimable list and
its spinlock ...
Then this can be an infrastructure change patch, which doesn't bring any
functional change, to support the non-reclaimable list.
> > +struct sgx_epc_lru_lists {
> > + /* Must acquire this lock to access */
> > + spinlock_t lock;
>
> Isn't this self-explanatory, why the inline comment?
I got a warning from the checkpatch script complaining this lock needs
comments.
I suspected this, so I applied this patch, removed the comment,
generated a new
patch, and run checkpatch.pl for it. It didn't report any warning/error
in my
testing.
Are you sure you got a warning?
I did a reran and it's actually a "CHECK" I got:
$ ./scripts/checkpatch.pl --strict
0001-x86-sgx-Add-struct-sgx_epc_lru_lists-to-encapsulate-.patch
CHECK: spinlock_t definition without comment
#41: FILE: arch/x86/kernel/cpu/sgx/sgx.h:101:
+ spinlock_t lock;
total: 0 errors, 0 warnings, 1 checks, 22 lines checked
Thanks
Haitao
