| Message ID | c112aad16eb47808e1ec10abd87b3d273c969a68.1677704283.git.christophe.jaillet@wanadoo.fr (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | ae2ade4ba58167f165fbf3db19380f9b72c56db8 |
| Headers | show |
| Series | spi: Reorder fields in 'struct spi_message' | expand |
On 3/2/23 1:58 AM, Christophe JAILLET wrote: > Group some variables based on their sizes to reduce hole and avoid padding. > On x86_64, this shrinks the size from 112 to 96 bytes. > > This should have no real impact on memory allocation because 'struct > spi_message' is mostly used on stack, but it can save a few cycles > when the structure is initialized with spi_message_init() and co. > > Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr> Tested-by: Muhammad Usama Anjum <usama.anjum@collabora.com> Reviewed-by: Muhammad Usama Anjum <usama.anjum@collabora.com> > --- > Using pahole > > Before: > ====== > struct spi_message { > struct list_head transfers; /* 0 16 */ > struct spi_device * spi; /* 16 8 */ > unsigned int is_dma_mapped:1; /* 24: 0 4 */ > > /* XXX 31 bits hole, try to pack */ > /* XXX 4 bytes hole, try to pack */ > > void (*complete)(void *); /* 32 8 */ > void * context; /* 40 8 */ > unsigned int frame_length; /* 48 4 */ > unsigned int actual_length; /* 52 4 */ > int status; /* 56 4 */ > > /* XXX 4 bytes hole, try to pack */ > > /* --- cacheline 1 boundary (64 bytes) --- */ > struct list_head queue; /* 64 16 */ > void * state; /* 80 8 */ > struct list_head resources; /* 88 16 */ > bool prepared; /* 104 1 */ > > /* size: 112, cachelines: 2, members: 12 */ > /* sum members: 93, holes: 2, sum holes: 8 */ > /* sum bitfield members: 1 bits, bit holes: 1, sum bit holes: 31 bits */ > /* padding: 7 */ > /* last cacheline: 48 bytes */ > }; > > > After: > ===== > struct spi_message { > struct list_head transfers; /* 0 16 */ > struct spi_device * spi; /* 16 8 */ > unsigned int is_dma_mapped:1; /* 24: 0 4 */ > > /* XXX 7 bits hole, try to pack */ > /* Bitfield combined with next fields */ > > bool prepared; /* 25 1 */ > > /* XXX 2 bytes hole, try to pack */ > > int status; /* 28 4 */ > void (*complete)(void *); /* 32 8 */ > void * context; /* 40 8 */ > unsigned int frame_length; /* 48 4 */ > unsigned int actual_length; /* 52 4 */ > struct list_head queue; /* 56 16 */ > /* --- cacheline 1 boundary (64 bytes) was 8 bytes ago --- */ > void * state; /* 72 8 */ > struct list_head resources; /* 80 16 */ > > /* size: 96, cachelines: 2, members: 12 */ > /* sum members: 93, holes: 1, sum holes: 2 */ > /* sum bitfield members: 1 bits, bit holes: 1, sum bit holes: 7 bits */ > /* last cacheline: 32 bytes */ > }; > --- > include/linux/spi/spi.h | 8 ++++---- > 1 file changed, 4 insertions(+), 4 deletions(-) > > diff --git a/include/linux/spi/spi.h b/include/linux/spi/spi.h > index 4fa26b9a3572..bdb35a91b4bf 100644 > --- a/include/linux/spi/spi.h > +++ b/include/linux/spi/spi.h > @@ -1093,6 +1093,9 @@ struct spi_message { > > unsigned is_dma_mapped:1; > > + /* spi_prepare_message() was called for this message */ > + bool prepared; > + > /* REVISIT: we might want a flag affecting the behavior of the > * last transfer ... allowing things like "read 16 bit length L" > * immediately followed by "read L bytes". Basically imposing > @@ -1105,11 +1108,11 @@ struct spi_message { > */ > > /* Completion is reported through a callback */ > + int status; > void (*complete)(void *context); > void *context; > unsigned frame_length; > unsigned actual_length; > - int status; > > /* For optional use by whatever driver currently owns the > * spi_message ... between calls to spi_async and then later > @@ -1120,9 +1123,6 @@ struct spi_message { > > /* List of spi_res reources when the spi message is processed */ > struct list_head resources; > - > - /* spi_prepare_message() was called for this message */ > - bool prepared; > }; > > static inline void spi_message_init_no_memset(struct spi_message *m)
On Wed, 01 Mar 2023 21:58:52 +0100, Christophe JAILLET wrote: > Group some variables based on their sizes to reduce hole and avoid padding. > On x86_64, this shrinks the size from 112 to 96 bytes. > > This should have no real impact on memory allocation because 'struct > spi_message' is mostly used on stack, but it can save a few cycles > when the structure is initialized with spi_message_init() and co. > > [...] Applied to https://git.kernel.org/pub/scm/linux/kernel/git/broonie/spi.git for-next Thanks! [1/1] spi: Reorder fields in 'struct spi_message' commit: ae2ade4ba58167f165fbf3db19380f9b72c56db8 All being well this means that it will be integrated into the linux-next tree (usually sometime in the next 24 hours) and sent to Linus during the next merge window (or sooner if it is a bug fix), however if problems are discovered then the patch may be dropped or reverted. You may get further e-mails resulting from automated or manual testing and review of the tree, please engage with people reporting problems and send followup patches addressing any issues that are reported if needed. If any updates are required or you are submitting further changes they should be sent as incremental updates against current git, existing patches will not be replaced. Please add any relevant lists and maintainers to the CCs when replying to this mail. Thanks, Mark
diff --git a/include/linux/spi/spi.h b/include/linux/spi/spi.h index 4fa26b9a3572..bdb35a91b4bf 100644 --- a/include/linux/spi/spi.h +++ b/include/linux/spi/spi.h @@ -1093,6 +1093,9 @@ struct spi_message { unsigned is_dma_mapped:1; + /* spi_prepare_message() was called for this message */ + bool prepared; + /* REVISIT: we might want a flag affecting the behavior of the * last transfer ... allowing things like "read 16 bit length L" * immediately followed by "read L bytes". Basically imposing @@ -1105,11 +1108,11 @@ struct spi_message { */ /* Completion is reported through a callback */ + int status; void (*complete)(void *context); void *context; unsigned frame_length; unsigned actual_length; - int status; /* For optional use by whatever driver currently owns the * spi_message ... between calls to spi_async and then later @@ -1120,9 +1123,6 @@ struct spi_message { /* List of spi_res reources when the spi message is processed */ struct list_head resources; - - /* spi_prepare_message() was called for this message */ - bool prepared; }; static inline void spi_message_init_no_memset(struct spi_message *m)
Group some variables based on their sizes to reduce hole and avoid padding. On x86_64, this shrinks the size from 112 to 96 bytes. This should have no real impact on memory allocation because 'struct spi_message' is mostly used on stack, but it can save a few cycles when the structure is initialized with spi_message_init() and co. Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr> --- Using pahole Before: ====== struct spi_message { struct list_head transfers; /* 0 16 */ struct spi_device * spi; /* 16 8 */ unsigned int is_dma_mapped:1; /* 24: 0 4 */ /* XXX 31 bits hole, try to pack */ /* XXX 4 bytes hole, try to pack */ void (*complete)(void *); /* 32 8 */ void * context; /* 40 8 */ unsigned int frame_length; /* 48 4 */ unsigned int actual_length; /* 52 4 */ int status; /* 56 4 */ /* XXX 4 bytes hole, try to pack */ /* --- cacheline 1 boundary (64 bytes) --- */ struct list_head queue; /* 64 16 */ void * state; /* 80 8 */ struct list_head resources; /* 88 16 */ bool prepared; /* 104 1 */ /* size: 112, cachelines: 2, members: 12 */ /* sum members: 93, holes: 2, sum holes: 8 */ /* sum bitfield members: 1 bits, bit holes: 1, sum bit holes: 31 bits */ /* padding: 7 */ /* last cacheline: 48 bytes */ }; After: ===== struct spi_message { struct list_head transfers; /* 0 16 */ struct spi_device * spi; /* 16 8 */ unsigned int is_dma_mapped:1; /* 24: 0 4 */ /* XXX 7 bits hole, try to pack */ /* Bitfield combined with next fields */ bool prepared; /* 25 1 */ /* XXX 2 bytes hole, try to pack */ int status; /* 28 4 */ void (*complete)(void *); /* 32 8 */ void * context; /* 40 8 */ unsigned int frame_length; /* 48 4 */ unsigned int actual_length; /* 52 4 */ struct list_head queue; /* 56 16 */ /* --- cacheline 1 boundary (64 bytes) was 8 bytes ago --- */ void * state; /* 72 8 */ struct list_head resources; /* 80 16 */ /* size: 96, cachelines: 2, members: 12 */ /* sum members: 93, holes: 1, sum holes: 2 */ /* sum bitfield members: 1 bits, bit holes: 1, sum bit holes: 7 bits */ /* last cacheline: 32 bytes */ }; --- include/linux/spi/spi.h | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-)