| Message ID | d47800d9fd5ac7c33d01af04b12b6d43ad23c96e.1676379187.git.christophe.jaillet@wanadoo.fr (mailing list archive) |
|---|---|
| State | Changes Requested |
| Delegated to: | Jason Gunthorpe |
| Headers | show |
| Series | RDMA/restrack: Reorder fields in 'struct rdma_restrack_entry' | expand |
On Tue, Feb 14, 2023 at 01:53:52PM +0100, Christophe JAILLET wrote: > diff --git a/include/rdma/restrack.h b/include/rdma/restrack.h > index 8b7c46daeb07..da53fefe6f9e 100644 > --- a/include/rdma/restrack.h > +++ b/include/rdma/restrack.h > @@ -80,6 +80,10 @@ struct rdma_restrack_entry { > * query stage. > */ > u8 no_track : 1; > + /** > + * @user: user resource > + */ > + bool user; Can we combine this into the bitfield above? Jason
Le 14/02/2023 à 14:08, Jason Gunthorpe a écrit : > On Tue, Feb 14, 2023 at 01:53:52PM +0100, Christophe JAILLET wrote: >> diff --git a/include/rdma/restrack.h b/include/rdma/restrack.h >> index 8b7c46daeb07..da53fefe6f9e 100644 >> --- a/include/rdma/restrack.h >> +++ b/include/rdma/restrack.h >> @@ -80,6 +80,10 @@ struct rdma_restrack_entry { >> * query stage. >> */ >> u8 no_track : 1; >> + /** >> + * @user: user resource >> + */ >> + bool user; > > Can we combine this into the bitfield above? > > Jason > Hi, and even above, we have bool valid; I wanted to keep the changes as minimal as possible, but I can change them all in a single bitfield. Do you want code such as: static void rdma_restrack_attach_task(struct rdma_restrack_entry *res, struct task_struct *task) { if (WARN_ON_ONCE(!task)) return; if (res->task) put_task_struct(res->task); get_task_struct(task); res->task = task; res->user = true; <-------- } to be changed with 0/1 instead of false/true? Apparently gcc 11.3 is fine with using true with u8:1, but I don't find it really logical. CJ
On Tue, Feb 14, 2023 at 03:34:21PM +0100, Christophe JAILLET wrote: > Le 14/02/2023 à 14:08, Jason Gunthorpe a écrit : > > On Tue, Feb 14, 2023 at 01:53:52PM +0100, Christophe JAILLET wrote: > > > diff --git a/include/rdma/restrack.h b/include/rdma/restrack.h > > > index 8b7c46daeb07..da53fefe6f9e 100644 > > > --- a/include/rdma/restrack.h > > > +++ b/include/rdma/restrack.h > > > @@ -80,6 +80,10 @@ struct rdma_restrack_entry { > > > * query stage. > > > */ > > > u8 no_track : 1; > > > + /** > > > + * @user: user resource > > > + */ > > > + bool user; > > > > Can we combine this into the bitfield above? > > > > Jason > > > Hi, > > and even above, we have > bool valid; > > I wanted to keep the changes as minimal as possible, but I can change them > all in a single bitfield. IIRC it needs to be checked, I vaugely remember valid can't be a bitfield because it is an atomic > Do you want code such as: > static void rdma_restrack_attach_task(struct rdma_restrack_entry *res, > struct task_struct *task) > { > if (WARN_ON_ONCE(!task)) > return; > > if (res->task) > put_task_struct(res->task); > get_task_struct(task); > res->task = task; > res->user = true; <-------- > } > > to be changed with 0/1 instead of false/true? I'd keep with true/false Ideally the bitfield itself would be bool type too > Apparently gcc 11.3 is fine with using true with u8:1, but I don't find it > really logical. Bool types can be casted to integers in defined ways, it is pretty normal. Jason
On Tue, Feb 14, 2023 at 11:01:00AM -0400, Jason Gunthorpe wrote: > On Tue, Feb 14, 2023 at 03:34:21PM +0100, Christophe JAILLET wrote: > > Le 14/02/2023 à 14:08, Jason Gunthorpe a écrit : > > > On Tue, Feb 14, 2023 at 01:53:52PM +0100, Christophe JAILLET wrote: > > > > diff --git a/include/rdma/restrack.h b/include/rdma/restrack.h > > > > index 8b7c46daeb07..da53fefe6f9e 100644 > > > > --- a/include/rdma/restrack.h > > > > +++ b/include/rdma/restrack.h > > > > @@ -80,6 +80,10 @@ struct rdma_restrack_entry { > > > > * query stage. > > > > */ > > > > u8 no_track : 1; > > > > + /** > > > > + * @user: user resource > > > > + */ > > > > + bool user; > > > > > > Can we combine this into the bitfield above? > > > > > > Jason > > > > > Hi, > > > > and even above, we have > > bool valid; > > > > I wanted to keep the changes as minimal as possible, but I can change them > > all in a single bitfield. > > IIRC it needs to be checked, I vaugely remember valid can't be a > bitfield because it is an atomic I don't remember anything like this. Thanks
Le 15/02/2023 à 12:31, Leon Romanovsky a écrit : > On Tue, Feb 14, 2023 at 11:01:00AM -0400, Jason Gunthorpe wrote: >> On Tue, Feb 14, 2023 at 03:34:21PM +0100, Christophe JAILLET wrote: >>> Le 14/02/2023 à 14:08, Jason Gunthorpe a écrit : >>>> On Tue, Feb 14, 2023 at 01:53:52PM +0100, Christophe JAILLET wrote: >>>>> diff --git a/include/rdma/restrack.h b/include/rdma/restrack.h >>>>> index 8b7c46daeb07..da53fefe6f9e 100644 >>>>> --- a/include/rdma/restrack.h >>>>> +++ b/include/rdma/restrack.h >>>>> @@ -80,6 +80,10 @@ struct rdma_restrack_entry { >>>>> * query stage. >>>>> */ >>>>> u8 no_track : 1; >>>>> + /** >>>>> + * @user: user resource >>>>> + */ >>>>> + bool user; >>>> >>>> Can we combine this into the bitfield above? >>>> >>>> Jason >>>> >>> Hi, >>> >>> and even above, we have >>> bool valid; >>> >>> I wanted to keep the changes as minimal as possible, but I can change them >>> all in a single bitfield. >> >> IIRC it needs to be checked, I vaugely remember valid can't be a >> bitfield because it is an atomic > > I don't remember anything like this. > > Thanks > If I understand code correctly, 'valid' is only used in rdma_restrack_add() and rdma_restrack_del(). I don't think that any atomic behavior is in place in these functions. I'll send in the coming days a v2 which changes 'valid', 'no_track' and 'user' as bool:1. CJ
diff --git a/include/rdma/restrack.h b/include/rdma/restrack.h index 8b7c46daeb07..da53fefe6f9e 100644 --- a/include/rdma/restrack.h +++ b/include/rdma/restrack.h @@ -80,6 +80,10 @@ struct rdma_restrack_entry { * query stage. */ u8 no_track : 1; + /** + * @user: user resource + */ + bool user; /* * @kref: Protect destroy of the resource */ @@ -106,10 +110,6 @@ struct rdma_restrack_entry { * @type: various objects in restrack database */ enum rdma_restrack_type type; - /** - * @user: user resource - */ - bool user; /** * @id: ID to expose to users */
Group some variables based on their sizes to reduce hole and avoid padding. On x86_64, this shrinks the size from 136 to 128 bytes. Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr> --- Using pahole Before: ====== struct rdma_restrack_entry { bool valid; /* 0 1 */ u8 no_track:1; /* 1: 0 1 */ /* XXX 7 bits hole, try to pack */ /* XXX 2 bytes hole, try to pack */ struct kref kref; /* 4 4 */ struct completion comp; /* 8 96 */ /* --- cacheline 1 boundary (64 bytes) was 40 bytes ago --- */ struct task_struct * task; /* 104 8 */ const char * kern_name; /* 112 8 */ enum rdma_restrack_type type; /* 120 4 */ bool user; /* 124 1 */ /* XXX 3 bytes hole, try to pack */ /* --- cacheline 2 boundary (128 bytes) --- */ u32 id; /* 128 4 */ /* size: 136, cachelines: 3, members: 9 */ /* sum members: 126, holes: 2, sum holes: 5 */ /* sum bitfield members: 1 bits, bit holes: 1, sum bit holes: 7 bits */ /* padding: 4 */ /* last cacheline: 8 bytes */ }; After: ===== struct rdma_restrack_entry { bool valid; /* 0 1 */ u8 no_track:1; /* 1: 0 1 */ /* XXX 7 bits hole, try to pack */ bool user; /* 2 1 */ /* XXX 1 byte hole, try to pack */ struct kref kref; /* 4 4 */ struct completion comp; /* 8 96 */ /* --- cacheline 1 boundary (64 bytes) was 40 bytes ago --- */ struct task_struct * task; /* 104 8 */ const char * kern_name; /* 112 8 */ enum rdma_restrack_type type; /* 120 4 */ u32 id; /* 124 4 */ /* size: 128, cachelines: 2, members: 9 */ /* sum members: 126, holes: 1, sum holes: 1 */ /* sum bitfield members: 1 bits, bit holes: 1, sum bit holes: 7 bits */ }; --- include/rdma/restrack.h | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-)