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Remove zero initialization of large buffers

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Profiles show that an high amount of CPU time spent in memset.
By removing zero initalization of certain large buffers we improve
performance in certain authoritative workloads.
This commit is contained in:
alessio
2025-01-30 12:33:48 +01:00
committed by xoranth
parent 9d4bf476d8
commit 4017a40b1d
3 changed files with 78 additions and 21 deletions
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31
lib/dns/qpcache.c
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@@ -1458,6 +1458,29 @@ find_coveringnsec(qpc_search_t *search, const dns_name_t *name,
(DNS_TRUST_PENDING((found)->trust) && \
(((options) & DNS_DBFIND_PENDINGOK) == 0)))
static void
qpc_search_init(qpc_search_t *search, qpcache_t *db, unsigned int options,
isc_stdtime_t now) {
/*
* qpc_search_t contains two structures with large buffers (dns_qpiter_t
* and dns_qpchain_t). Those two structures will be initialized later by
* dns_qp_lookup anyway.
* To avoid the overhead of zero initialization, we avoid designated
* initializers and initialize all "small" fields manually.
*/
search->qpdb = (qpcache_t *)db;
search->options = options;
/*
* qpch->in - Init by dns_qp_lookup
* qpiter - Init by dns_qp_lookup
*/
search->need_cleanup = false;
search->now = now ? now : isc_stdtime_now();
search->zonecut = NULL;
search->zonecut_header = NULL;
search->zonecut_sigheader = NULL;
}
static isc_result_t
qpcache_find(dns_db_t *db, const dns_name_t *name, dns_dbversion_t *version,
dns_rdatatype_t type, unsigned int options, isc_stdtime_t __now,
@@ -1479,11 +1502,9 @@ qpcache_find(dns_db_t *db, const dns_name_t *name, dns_dbversion_t *version,
dns_slabheader_t *foundsig = NULL, *nssig = NULL, *cnamesig = NULL;
dns_slabheader_t *nsecheader = NULL, *nsecsig = NULL;
dns_typepair_t sigtype, negtype;
qpc_search_t search = (qpc_search_t){
.qpdb = (qpcache_t *)db,
.options = options,
.now = __now ? __now : isc_stdtime_now(),
};
qpc_search_t search;
qpc_search_init(&search, (qpcache_t *)db, options, __now);
REQUIRE(VALID_QPDB((qpcache_t *)db));
REQUIRE(version == NULL);