[RFC PATCH v2 02/10] mm, swap: add CONFIG_XSWAP and xswap fields to swap_info_struct
Baoquan He <[email protected]>
| Newsgroups | gmane.linux.kernel,gmane.linux.kernel.mm |
|---|---|
| Message-ID | <[email protected]> |
Add CONFIG_XSWAP Kconfig option (depends on SWAP && 64BIT) for extendable (virtual) swap device support. Add three fields to struct swap_info_struct under CONFIG_XSWAP: - cluster_vm: the VM_SPARSE vm_struct backing the cluster_info array - nr_clusters: total number of clusters in the xswap address space - nr_clusters_mapped: number of clusters currently mapped (lazy grow) These fields enable lazy vmalloc-based dynamic cluster management where the cluster_info array is backed by a sparse vmalloc area that grows on demand and shrinks when clusters are freed. Signed-off-by: Baoquan He <[email protected]> --- include/linux/swap.h | 5 +++++ mm/Kconfig | 9 +++++++++ 2 files changed, 14 insertions(+) diff --git a/include/linux/swap.h b/include/linux/swap.h index 78f4302b92e1..970232f6359d 100644 --- a/include/linux/swap.h +++ b/include/linux/swap.h @@ -248,6 +248,11 @@ struct swap_info_struct { signed char type; /* strange name for an index */ unsigned int max; /* size of this swap device */ struct swap_cluster_info *cluster_info; /* cluster info. Only for SSD */ +#ifdef CONFIG_XSWAP + struct vm_struct *cluster_vm; /* VM_SPARSE area for xswap dynamic cluster_info */ + unsigned long nr_clusters; /* total cluster count for xswap */ + unsigned long nr_clusters_mapped; /* currently mapped cluster count */ +#endif struct list_head free_clusters; /* free clusters list */ struct list_head full_clusters; /* full clusters list */ struct list_head nonfull_clusters[SWAP_NR_ORDERS]; diff --git a/mm/Kconfig b/mm/Kconfig index 060190e12bce..82f62f4c5b23 100644 --- a/mm/Kconfig +++ b/mm/Kconfig @@ -122,6 +122,15 @@ config ZSWAP_COMPRESSOR_DEFAULT default "zstd" if ZSWAP_COMPRESSOR_DEFAULT_ZSTD default "" +config XSWAP + bool "Extendable (virtual) swap device" + depends on SWAP && 64BIT + help + Adds support for extendable swap devices (xswap) that decouple + PTE swap entries from physical backing storage. The cluster_info + array is backed by a sparse vmalloc area that grows and shrinks + on demand, avoiding static pre-allocation overhead. + config ZSMALLOC tristate -- 2.54.0