Am 06.08.2015 um 17:54 schrieb Rainer Jung:
I think the root cause is here (file subversion/libsvn_ra_svn/marshal.c):1082 /* Allocate an APR array with room for (initially) 4 items. 1083 * We do this manually because lists are the most frequent protocol 1084 * element, often used to frame a single, optional value. We save 1085 * about 20% of total protocol handling time. */ 1086 char *buffer = apr_palloc(pool, sizeof(apr_array_header_t) 1087 + 4 * sizeof(svn_ra_svn_item_t)); 1088 svn_ra_svn_item_t *data 1089 = (svn_ra_svn_item_t *)(buffer + sizeof(apr_array_header_t)); 1090 1091 item->kind = SVN_RA_SVN_LIST; 1092 item->u.list = (apr_array_header_t *)buffer; "buffer" is not specifically aligned, the array members in "item->u.list = (apr_array_header_t *)buffer" could be misaligned. The following (ugly) workaround fixes it for me: --- subversion/libsvn_ra_svn/marshal.c.kpdt_orig Fri Feb 13 12:17:40 2015 +++ subversion/libsvn_ra_svn/marshal.c Thu Aug 6 17:46:58 2015 @@ -1083,10 +1083,16 @@ * We do this manually because lists are the most frequent protocol * element, often used to frame a single, optional value. We save * about 20% of total protocol handling time. */ - char *buffer = apr_palloc(pool, sizeof(apr_array_header_t) + + /* Make sure the data part of the buffer has appropriate alignment + by prefixing it with a size that fits the needed apr_array_header_t + but is itself highly aligned. */ + size_t offset = sizeof(apr_array_header_t) / 8 * 8; + + char *buffer = apr_palloc(pool, offset + 4 * sizeof(svn_ra_svn_item_t)); svn_ra_svn_item_t *data - = (svn_ra_svn_item_t *)(buffer + sizeof(apr_array_header_t)); + = (svn_ra_svn_item_t *)(buffer + offset); item->kind = SVN_RA_SVN_LIST; item->u.list = (apr_array_header_t *)buffer; But of course its a bit rough, because it would apply on all platforms, even if not needed. Also on some (future?) platforms, the alignment for 8 bytes might not always be correct. It's a bit tragic that this code part is prefixed with: * We do this manually because lists are the most frequent protocol * element, often used to frame a single, optional value. We save * about 20% of total protocol handling time. */ and the trap is that doing it manually often is harder than expected. Switching to apr_array_make() would have not introduced this bug, but of course you did it for a reason.
The switch was introduced in r1485851. It is not part of 1.7 or 1.8. Regards, Rainer
