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PDU reduce number of mallocs/memcpys in iscsi_add_data()

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This patch adds logarithmic malloc behaviour to iscsi_add_data().
Currently for each new call there is a new buffer allocated
and all old data is copied to the new buffer. Change this by
allocating at least PAGE_SIZE bytes and increase the allocation
by powers of 2 each time it does no longer fit.
This commit is contained in:
Peter Lieven
2012-11-03 02:49:56 +01:00
parent d9fbe37f4b
commit c4dc380262
2 changed files with 20 additions and 11 deletions
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29
lib/pdu.c
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@@ -107,7 +107,6 @@ iscsi_add_data(struct iscsi_context *iscsi, struct iscsi_data *data,
unsigned char *dptr, int dsize, int pdualignment)
{
int len, aligned;
unsigned char *buf;
if (dsize == 0) {
iscsi_set_error(iscsi, "Trying to append zero size data to "
@@ -121,25 +120,33 @@ iscsi_add_data(struct iscsi_context *iscsi, struct iscsi_data *data,
aligned = (aligned+3)&0xfffffffc;
}
buf = iscsi_malloc(iscsi, aligned);
if (buf == NULL) {
int new_alloc_size=data->alloc_size;
if (new_alloc_size < PAGE_SIZE) new_alloc_size=PAGE_SIZE;
while (aligned > new_alloc_size) new_alloc_size<<=1;
if (data->data != NULL && data->alloc_size == 0) data->alloc_size=data->size;
if (data->alloc_size == 0)
data->data = iscsi_malloc(iscsi, new_alloc_size);
else
if (data->alloc_size != new_alloc_size)
data->data = realloc(data->data, new_alloc_size);
if (data->data == NULL) {
iscsi_set_error(iscsi, "failed to allocate buffer for %d "
"bytes", len);
return -1;
}
data->alloc_size = new_alloc_size;
memcpy(data->data + data->size, dptr, dsize);
if (data->size > 0) {
memcpy(buf, data->data, data->size);
}
memcpy(buf + data->size, dptr, dsize);
if (len != aligned) {
/* zero out any padding at the end */
memset(buf+len, 0, aligned-len);
memset(data->data+len, 0, aligned-len);
}
iscsi_free(iscsi, data->data);
data->data = buf;
data->size = len;
return 0;