nfsd: give out fewer session slots as limit approaches

Instead of granting client's full requests until we hit our DRC size
limit and then failing CREATE_SESSIONs (and hence mounts) completely,
start granting clients smaller slot tables as we approach the limit.

The factor chosen here is pretty much arbitrary.

Signed-off-by: J. Bruce Fields <bfields@redhat.com>
This commit is contained in:
J. Bruce Fields 2017-09-19 19:25:41 -04:00
parent 44d8660d3b
commit de766e5704

View File

@ -1472,6 +1472,11 @@ static u32 nfsd4_get_drc_mem(struct nfsd4_channel_attrs *ca)
spin_lock(&nfsd_drc_lock); spin_lock(&nfsd_drc_lock);
avail = min((unsigned long)NFSD_MAX_MEM_PER_SESSION, avail = min((unsigned long)NFSD_MAX_MEM_PER_SESSION,
nfsd_drc_max_mem - nfsd_drc_mem_used); nfsd_drc_max_mem - nfsd_drc_mem_used);
/*
* Never use more than a third of the remaining memory,
* unless it's the only way to give this client a slot:
*/
avail = clamp_t(int, avail, slotsize, avail/3);
num = min_t(int, num, avail / slotsize); num = min_t(int, num, avail / slotsize);
nfsd_drc_mem_used += num * slotsize; nfsd_drc_mem_used += num * slotsize;
spin_unlock(&nfsd_drc_lock); spin_unlock(&nfsd_drc_lock);