On 2/21/20 2:53 AM, John Hubbard wrote: > On 2/20/20 7:01 AM, Joel Savitz wrote: >> >> Currently, the vm.min_free_kbytes sysctl value is capped at a hardcoded >> 64M in init_per_zone_wmark_min (unless it is overridden by khugepaged >> initialization). >> >> This value has not been modified since 2005, and enterprise-grade >> systems now frequently have hundreds of GB of RAM and multiple 10, 40, >> or even 100 GB NICs. We have seen page allocation failures on heavily >> loaded systems related to NIC drivers. These issues were resolved by an >> increase to vm.min_free_kbytes. >> >> This patch increases the hardcoded value by a factor of 4 as a temporary >> solution. >> >> Further work to make the calculation of vm.min_free_kbytes more >> consistent throughout the kernel would be desirable. >> >> As an example of the inconsistency of the current method, this value is >> recalculated by init_per_zone_wmark_min() in the case of memory hotplug >> which will override the value set by set_recommended_min_free_kbytes() >> called during khugepaged initialization even if khugepaged remains >> enabled, however an on/off toggle of khugepaged will then recalculate >> and set the value via set_recommended_min_free_kbytes(). >> >> Signed-off-by: Joel Savitz <jsavitz@xxxxxxxxxx> >> --- >> mm/page_alloc.c | 4 ++-- >> 1 file changed, 2 insertions(+), 2 deletions(-) >> >> diff --git a/mm/page_alloc.c b/mm/page_alloc.c >> index 3c4eb750a199..32cbfb13e958 100644 >> --- a/mm/page_alloc.c >> +++ b/mm/page_alloc.c >> @@ -7867,8 +7867,8 @@ int __meminit init_per_zone_wmark_min(void) >> min_free_kbytes = new_min_free_kbytes; >> if (min_free_kbytes < 128) >> min_free_kbytes = 128; >> - if (min_free_kbytes > 65536) >> - min_free_kbytes = 65536; >> + if (min_free_kbytes > 262144) >> + min_free_kbytes = 262144; > > > Would it be any better to at least use symbols, instead of numbers, in the > routine? Like this: +1 Thanks
