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Merge team/russell/iax2_performance.

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There is not a large amount of code here and the changes are not very invasive.
However, they should significantly improve performance of chan_iax2 under load.

IAX2 media frames only carry the *source* call number.  So, when one arrives,
the correct session that it is a part of has to be matched on IP address, port
number, and call number, instead of just a call number.  Had these frames
carried the *destination* call number, this would not be an issue, because that
would be a unique identifier that would make it easy to immediately identify
the correct session.

The way that chan_iax2 did this matching was extremely inefficient.  It starts
at the first available call number and traverses each call number sequentially,
locking and unlocking a mutex for each one, to try to match against it.  It
would do this regardless of whether the call number was in use or not.  So,
for a call with a local call number of 25000, every single incoming media
frame would require a traversal that required 25000 mutex lock and unlock
operations.  (Note that the max call number is about 32k).

I have introduced a hash table of active IAX2 calls to improve this lookup
process.  The hash is done on the IP address, port number, and call number.  
So, for the previous example, a few lock/unlock operations may be done versus 
25000 for each frame.


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@56447 65c4cc65-6c06-0410-ace0-fbb531ad65f3
This commit is contained in:
Russell Bryant
2007-02-23 21:20:33 +00:00
parent 78a062ac07
commit 9fb1404279
1 changed files with 65 additions and 16 deletions
Download Patch File Download Diff File Expand all files Collapse all files

81
channels/chan_iax2.c
View File

@@ -631,8 +631,15 @@ struct chan_iax2_pvt {
int frames_dropped;
/*! received frame count: (just for stats) */
int frames_received;
AST_LIST_ENTRY(chan_iax2_pvt) entry;
unsigned int hash;
};
/* Somewhat arbitrary prime number */
#define PVT_HASH_SIZE 563
static AST_RWLIST_HEAD(pvt_list, chan_iax2_pvt) pvt_hash_tbl[PVT_HASH_SIZE];
static AST_LIST_HEAD_STATIC(queue, iax_frame);
static AST_LIST_HEAD_STATIC(users, iax2_user);
@@ -1258,20 +1265,32 @@ static int make_trunk(unsigned short callno, int locked)
return res;
}
/*!
* \todo XXX Note that this function contains a very expensive operation that
* happens for *every* incoming media frame. It iterates through every
* possible call number, locking and unlocking each one, to try to match the
* incoming frame to an active call. Call numbers can be up to 2^15, 32768.
* So, for an call with a local call number of 20000, every incoming audio
* frame would require 20000 mutex lock and unlock operations. Ouch.
*
* It's a shame that IAX2 media frames carry the source call number instead of
* the destination call number. If they did, this lookup wouldn't be needed.
* However, it's too late to change that now. Instead, we need to come up with
* a better way of indexing active calls so that these frequent lookups are not
* so expensive.
*/
static inline unsigned int peer_hash_val(const struct sockaddr_in *sin, unsigned short callno)
{
return ( (sin->sin_addr.s_addr & 0xFF000000) ^
(sin->sin_addr.s_addr & 0x00FF0000) ^
(sin->sin_addr.s_addr & 0x0000FF00) ^
(sin->sin_addr.s_addr & 0x000000FF) ^
(sin->sin_port & 0xFF00) ^ (sin->sin_port ^ 0x00FF) ^
(callno & 0xFF00) ^ (callno & 0x00FF) )
% PVT_HASH_SIZE;
}
static inline void hash_on_peer(struct chan_iax2_pvt *pvt)
{
if (pvt->hash) {
AST_RWLIST_WRLOCK(&pvt_hash_tbl[pvt->hash]);
AST_RWLIST_REMOVE(&pvt_hash_tbl[pvt->hash], pvt, entry);
AST_RWLIST_UNLOCK(&pvt_hash_tbl[pvt->hash]);
}
pvt->hash = peer_hash_val(&pvt->addr, pvt->peercallno);
AST_RWLIST_WRLOCK(&pvt_hash_tbl[pvt->hash]);
AST_RWLIST_INSERT_HEAD(&pvt_hash_tbl[pvt->hash], pvt, entry);
AST_RWLIST_UNLOCK(&pvt_hash_tbl[pvt->hash]);
}
static int find_callno(unsigned short callno, unsigned short dcallno, struct sockaddr_in *sin, int new, int lockpeer, int sockfd)
{
int res = 0;
@@ -1279,7 +1298,19 @@ static int find_callno(unsigned short callno, unsigned short dcallno, struct soc
struct timeval now;
char host[80];
if (new <= NEW_ALLOW) {
/* Look for an existing connection first */
unsigned int hash = peer_hash_val(sin, callno);
const struct chan_iax2_pvt *pvt;
AST_RWLIST_RDLOCK(&pvt_hash_tbl[hash]);
AST_RWLIST_TRAVERSE(&pvt_hash_tbl[hash], pvt, entry) {
ast_mutex_lock(&iaxsl[pvt->callno]);
if (match(sin, callno, dcallno, iaxs[pvt->callno]))
res = pvt->callno;
ast_mutex_unlock(&iaxsl[pvt->callno]);
if (res > 0)
break;
}
AST_RWLIST_UNLOCK(&pvt_hash_tbl[hash]);
/* Not hashed yet, Look for an existing connection */
for (x=1;(res < 1) && (x<maxnontrunkcall);x++) {
ast_mutex_lock(&iaxsl[x]);
if (iaxs[x]) {
@@ -1326,6 +1357,7 @@ static int find_callno(unsigned short callno, unsigned short dcallno, struct soc
iaxs[x]->addr.sin_family = sin->sin_family;
iaxs[x]->addr.sin_addr.s_addr = sin->sin_addr.s_addr;
iaxs[x]->peercallno = callno;
hash_on_peer(iaxs[x]);
iaxs[x]->callno = x;
iaxs[x]->pingtime = DEFAULT_RETRY_TIME;
iaxs[x]->expiry = min_reg_expire;
@@ -1810,6 +1842,12 @@ retry:
pvt->owner = NULL;
iax2_destroy_helper(pvt);
if (pvt->hash) {
AST_RWLIST_WRLOCK(&pvt_hash_tbl[pvt->hash]);
AST_RWLIST_REMOVE(&pvt_hash_tbl[pvt->hash], pvt, entry);
AST_RWLIST_UNLOCK(&pvt_hash_tbl[pvt->hash]);
}
/* Already gone */
ast_set_flag(pvt, IAX_ALREADYGONE);
@@ -5406,6 +5444,7 @@ static int complete_transfer(int callno, struct iax_ies *ies)
pvt->iseqno = 0;
pvt->aseqno = 0;
pvt->peercallno = peercallno;
hash_on_peer(pvt);
pvt->transferring = TRANSFER_NONE;
pvt->svoiceformat = -1;
pvt->voiceformat = 0;
@@ -6616,8 +6655,12 @@ static int socket_process(struct iax2_thread *thread)
if (!inaddrcmp(&sin, &iaxs[fr->callno]->addr) && !minivid &&
f.subclass != IAX_COMMAND_TXCNT && /* for attended transfer */
f.subclass != IAX_COMMAND_TXACC) /* for attended transfer */
f.subclass != IAX_COMMAND_TXACC) { /* for attended transfer */
iaxs[fr->callno]->peercallno = (unsigned short)(ntohs(mh->callno) & ~IAX_FLAG_FULL);
ast_mutex_unlock(&iaxsl[fr->callno]);
hash_on_peer(iaxs[fr->callno]);
ast_mutex_lock(&iaxsl[fr->callno]);
}
if (ntohs(mh->callno) & IAX_FLAG_FULL) {
if (option_debug && iaxdebug)
ast_log(LOG_DEBUG, "Received packet %d, (%d, %d)\n", fh->oseqno, f.frametype, f.subclass);
@@ -10103,6 +10146,9 @@ static int __unload_module(void)
for (x = 0; x < IAX_MAX_CALLS; x++)
ast_mutex_destroy(&iaxsl[x]);
for (x = 0; x < PVT_HASH_SIZE; x++)
AST_RWLIST_HEAD_DESTROY(&pvt_hash_tbl[x]);
return 0;
}
@@ -10144,6 +10190,9 @@ static int load_module(void)
for (x=0;x<IAX_MAX_CALLS;x++)
ast_mutex_init(&iaxsl[x]);
for (x = 0; x < PVT_HASH_SIZE; x++)
AST_RWLIST_HEAD_INIT(&pvt_hash_tbl[x]);
ast_cond_init(&sched_cond, NULL);
if (!(sched = sched_context_create())) {