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/freebsd-11-stable/usr.sbin/mountd/ | ||
H A D | mountd.c | diff 349756 Fri Jul 05 01:18:18 MDT 2019 rmacklem MFC: r348452 Replace a single linked list with a hash table of lists. mountd.c uses a single linked list of "struct exportlist" structures, where there is one of these for each exported file system on the NFS server. This list gets long if there are a large number of file systems exported and the list must be searched for each line in the exports file(s) when SIGHUP causes the exports file(s) to be reloaded. A simple benchmark that traverses SLIST() elements and compares two 32bit fields in the structure for equal (which is what the search is) appears to take a couple of nsec. So, for a server with 72000 exported file systems, this can take about 5sec during reload of the exports file(s). By replacing the single linked list with a hash table with a target of 10 elements per list, the time should be reduced to less than 1msec. Peter Errikson (who has a server with 72000+ exported file systems) ran a test program using 5 hashes to see how they worked. fnv_32_buf(fsid,..., 0) fnv_32_buf(fsid,..., FNV1_32_INIT) hash32_buf(fsid,..., 0) hash32_buf(fsid,..., HASHINIT) - plus simply using the low order bits of fsid.val[0]. The first three behaved about equally well, with the first one being slightly better than the others. It has an average variation of about 4.5% about the target list length and that is what this patch uses. Peter Errikson also tested this hash table version and found that the performance wasn't measurably improved by a larger hash table, so a load factor of 10 appears adequate. PR: 237860 diff 349756 Fri Jul 05 01:18:18 MDT 2019 rmacklem MFC: r348452 Replace a single linked list with a hash table of lists. mountd.c uses a single linked list of "struct exportlist" structures, where there is one of these for each exported file system on the NFS server. This list gets long if there are a large number of file systems exported and the list must be searched for each line in the exports file(s) when SIGHUP causes the exports file(s) to be reloaded. A simple benchmark that traverses SLIST() elements and compares two 32bit fields in the structure for equal (which is what the search is) appears to take a couple of nsec. So, for a server with 72000 exported file systems, this can take about 5sec during reload of the exports file(s). By replacing the single linked list with a hash table with a target of 10 elements per list, the time should be reduced to less than 1msec. Peter Errikson (who has a server with 72000+ exported file systems) ran a test program using 5 hashes to see how they worked. fnv_32_buf(fsid,..., 0) fnv_32_buf(fsid,..., FNV1_32_INIT) hash32_buf(fsid,..., 0) hash32_buf(fsid,..., HASHINIT) - plus simply using the low order bits of fsid.val[0]. The first three behaved about equally well, with the first one being slightly better than the others. It has an average variation of about 4.5% about the target list length and that is what this patch uses. Peter Errikson also tested this hash table version and found that the performance wasn't measurably improved by a larger hash table, so a load factor of 10 appears adequate. PR: 237860 |
/freebsd-11-stable/usr.sbin/config/ | ||
H A D | config.y | diff 72000 Sun Feb 04 11:17:38 MST 2001 peter Remove the need to list each and every cpu platform. Config will now take your word for the 'machine' switch. |
H A D | config.h | diff 72000 Sun Feb 04 11:17:38 MST 2001 peter Remove the need to list each and every cpu platform. Config will now take your word for the 'machine' switch. |
H A D | main.c | diff 72000 Sun Feb 04 11:17:38 MST 2001 peter Remove the need to list each and every cpu platform. Config will now take your word for the 'machine' switch. |
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