diff options
| -rw-r--r-- | Documentation/admin-guide/sysctl/vm.rst | 32 | ||||
| -rw-r--r-- | fs/dcache.c | 11 |
2 files changed, 31 insertions, 12 deletions
diff --git a/Documentation/admin-guide/sysctl/vm.rst b/Documentation/admin-guide/sysctl/vm.rst index 8290177b4f75..d385985b305f 100644 --- a/Documentation/admin-guide/sysctl/vm.rst +++ b/Documentation/admin-guide/sysctl/vm.rst @@ -75,6 +75,7 @@ Currently, these files are in /proc/sys/vm: - unprivileged_userfaultfd - user_reserve_kbytes - vfs_cache_pressure +- vfs_cache_pressure_denom - watermark_boost_factor - watermark_scale_factor - zone_reclaim_mode @@ -1017,19 +1018,28 @@ vfs_cache_pressure This percentage value controls the tendency of the kernel to reclaim the memory which is used for caching of directory and inode objects. -At the default value of vfs_cache_pressure=100 the kernel will attempt to -reclaim dentries and inodes at a "fair" rate with respect to pagecache and -swapcache reclaim. Decreasing vfs_cache_pressure causes the kernel to prefer -to retain dentry and inode caches. When vfs_cache_pressure=0, the kernel will -never reclaim dentries and inodes due to memory pressure and this can easily -lead to out-of-memory conditions. Increasing vfs_cache_pressure beyond 100 -causes the kernel to prefer to reclaim dentries and inodes. +At the default value of vfs_cache_pressure=vfs_cache_pressure_denom the kernel +will attempt to reclaim dentries and inodes at a "fair" rate with respect to +pagecache and swapcache reclaim. Decreasing vfs_cache_pressure causes the +kernel to prefer to retain dentry and inode caches. When vfs_cache_pressure=0, +the kernel will never reclaim dentries and inodes due to memory pressure and +this can easily lead to out-of-memory conditions. Increasing vfs_cache_pressure +beyond vfs_cache_pressure_denom causes the kernel to prefer to reclaim dentries +and inodes. -Increasing vfs_cache_pressure significantly beyond 100 may have negative -performance impact. Reclaim code needs to take various locks to find freeable -directory and inode objects. With vfs_cache_pressure=1000, it will look for -ten times more freeable objects than there are. +Increasing vfs_cache_pressure significantly beyond vfs_cache_pressure_denom may +have negative performance impact. Reclaim code needs to take various locks to +find freeable directory and inode objects. When vfs_cache_pressure equals +(10 * vfs_cache_pressure_denom), it will look for ten times more freeable +objects than there are. +Note: This setting should always be used together with vfs_cache_pressure_denom. + +vfs_cache_pressure_denom +======================== + +Defaults to 100 (minimum allowed value). Requires corresponding +vfs_cache_pressure setting to take effect. watermark_boost_factor ====================== diff --git a/fs/dcache.c b/fs/dcache.c index bd5aa136153a..ed46818c151c 100644 --- a/fs/dcache.c +++ b/fs/dcache.c @@ -74,10 +74,11 @@ * arbitrary, since it's serialized on rename_lock */ static int sysctl_vfs_cache_pressure __read_mostly = 100; +static int sysctl_vfs_cache_pressure_denom __read_mostly = 100; unsigned long vfs_pressure_ratio(unsigned long val) { - return mult_frac(val, sysctl_vfs_cache_pressure, 100); + return mult_frac(val, sysctl_vfs_cache_pressure, sysctl_vfs_cache_pressure_denom); } EXPORT_SYMBOL_GPL(vfs_pressure_ratio); @@ -225,6 +226,14 @@ static const struct ctl_table vm_dcache_sysctls[] = { .proc_handler = proc_dointvec_minmax, .extra1 = SYSCTL_ZERO, }, + { + .procname = "vfs_cache_pressure_denom", + .data = &sysctl_vfs_cache_pressure_denom, + .maxlen = sizeof(sysctl_vfs_cache_pressure_denom), + .mode = 0644, + .proc_handler = proc_dointvec_minmax, + .extra1 = SYSCTL_ONE_HUNDRED, + }, }; static int __init init_fs_dcache_sysctls(void) |