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1f106ff0ea
IOTLB device presence, iommu coherency and snooping are boolean
capabilities. Use them as bits and keep them adjacent.
Structure layout before the reorg.
$ pahole -C dmar_domain drivers/iommu/intel/dmar.o
struct dmar_domain {
int nid; /* 0 4 */
unsigned int iommu_refcnt[128]; /* 4 512 */
/* --- cacheline 8 boundary (512 bytes) was 4 bytes ago --- */
u16 iommu_did[128]; /* 516 256 */
/* --- cacheline 12 boundary (768 bytes) was 4 bytes ago --- */
bool has_iotlb_device; /* 772 1 */
/* XXX 3 bytes hole, try to pack */
struct list_head devices; /* 776 16 */
struct list_head subdevices; /* 792 16 */
struct iova_domain iovad __attribute__((__aligned__(8)));
/* 808 2320 */
/* --- cacheline 48 boundary (3072 bytes) was 56 bytes ago --- */
struct dma_pte * pgd; /* 3128 8 */
/* --- cacheline 49 boundary (3136 bytes) --- */
int gaw; /* 3136 4 */
int agaw; /* 3140 4 */
int flags; /* 3144 4 */
int iommu_coherency; /* 3148 4 */
int iommu_snooping; /* 3152 4 */
int iommu_count; /* 3156 4 */
int iommu_superpage; /* 3160 4 */
/* XXX 4 bytes hole, try to pack */
u64 max_addr; /* 3168 8 */
u32 default_pasid; /* 3176 4 */
/* XXX 4 bytes hole, try to pack */
struct iommu_domain domain; /* 3184 72 */
/* size: 3256, cachelines: 51, members: 18 */
/* sum members: 3245, holes: 3, sum holes: 11 */
/* forced alignments: 1 */
/* last cacheline: 56 bytes */
} __attribute__((__aligned__(8)));
After arranging it for natural padding and to make flags as u8 bits, it
saves 8 bytes for the struct.
struct dmar_domain {
int nid; /* 0 4 */
unsigned int iommu_refcnt[128]; /* 4 512 */
/* --- cacheline 8 boundary (512 bytes) was 4 bytes ago --- */
u16 iommu_did[128]; /* 516 256 */
/* --- cacheline 12 boundary (768 bytes) was 4 bytes ago --- */
u8 has_iotlb_device:1; /* 772: 0 1 */
u8 iommu_coherency:1; /* 772: 1 1 */
u8 iommu_snooping:1; /* 772: 2 1 */
/* XXX 5 bits hole, try to pack */
/* XXX 3 bytes hole, try to pack */
struct list_head devices; /* 776 16 */
struct list_head subdevices; /* 792 16 */
struct iova_domain iovad __attribute__((__aligned__(8)));
/* 808 2320 */
/* --- cacheline 48 boundary (3072 bytes) was 56 bytes ago --- */
struct dma_pte * pgd; /* 3128 8 */
/* --- cacheline 49 boundary (3136 bytes) --- */
int gaw; /* 3136 4 */
int agaw; /* 3140 4 */
int flags; /* 3144 4 */
int iommu_count; /* 3148 4 */
int iommu_superpage; /* 3152 4 */
/* XXX 4 bytes hole, try to pack */
u64 max_addr; /* 3160 8 */
u32 default_pasid; /* 3168 4 */
/* XXX 4 bytes hole, try to pack */
struct iommu_domain domain; /* 3176 72 */
/* size: 3248, cachelines: 51, members: 18 */
/* sum members: 3236, holes: 3, sum holes: 11 */
/* sum bitfield members: 3 bits, bit holes: 1, sum bit holes: 5 bits */
/* forced alignments: 1 */
/* last cacheline: 48 bytes */
} __attribute__((__aligned__(8)));
Signed-off-by: Parav Pandit <parav@nvidia.com>
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Link: https://lore.kernel.org/r/20210530075053.264218-1-parav@nvidia.com
Link: https://lore.kernel.org/r/20210610020115.1637656-20-baolu.lu@linux.intel.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>
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Linux kernel
============
There are several guides for kernel developers and users. These guides can
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Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
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https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.