 |
 |
Using a XrdOucBuffPool with the following parameters minsz=1024 and maxsz=1024*1024, the Alloc method fails to allocate a buffer of say 1482 bytes since the alignment used when calling posix_memalign is not a power of 2. This in turn happens since the size buffer slots used in the XrdOucBuffPool are in their turn not power of two but multiples of the minsz. Therefore, for example, we end up with buffer slots that look like this:
(gdb) p bSlot[0]
$10 = {SlotMutex = {cs = {__data = {__lock = 0, __count = 0, __owner = 0, __nusers = 0, __kind = 0, __spins = 0, __elision = 0, __list = {__prev = 0x0, __next = 0x0}}, __size = '\000' <repeats 39 times>, __align = 0}}, buffFree = 0x0, size = 1024, numbuff = 0, maxbuff = 16}
(gdb) p bSlot[1]
$11 = {SlotMutex = {cs = {__data = {__lock = 0, __count = 0, __owner = 0, __nusers = 0, __kind = 0, __spins = 0, __elision = 0, __list = {__prev = 0x0, __next = 0x0}}, __size = '\000' <repeats 39 times>, __align = 0}}, buffFree = 0x0, size = 2048, numbuff = 0, maxbuff = 16}
(gdb) p bSlot[2]
$12 = {SlotMutex = {cs = {__data = {__lock = 0, __count = 0, __owner = 0, __nusers = 0, __kind = 0, __spins = 0, __elision = 0, __list = {__prev = 0x0, __next = 0x0}}, __size = '\000' <repeats 39 times>, __align = 0}}, buffFree = 0x0, size = 3072, numbuff = 0, maxbuff = 14}
(gdb) p bSlot[3]
$13 = {SlotMutex = {cs = {__data = {__lock = 0, __count = 0, __owner = 0, __nusers = 0, __kind = 0, __spins = 0, __elision = 0, __list = {__prev = 0x0, __next = 0x0}}, __size = '\000' <repeats 39 times>, __align = 0}}, buffFree = 0x0, size = 4096, numbuff = 0, maxbuff = 13}
(gdb) p bSlot[4]
$14 = {SlotMutex = {cs = {__data = {__lock = 0, __count = 0, __owner = 0, __nusers = 0, __kind = 0, __spins = 0, __elision = 0, __list = {__prev = 0x0, __next = 0x0}}, __size = '\000' <repeats 39 times>, __align = 0}}, buffFree = 0x0, size = 5120, numbuff = 0, maxbuff = 12}
(gdb) bt
#0 XrdOucBuffPool::Alloc (this=this@entry=0x7f6db6f61f00 <eos::fst::gOFS+6208>, bsz=1472) at /usr/src/debug/xrootd-4.12.8/src/XrdOuc/XrdOucBuffer.cc:104
Notice that the size member in the BuffSlot object is used for the posix_memalign call as the alignment and this will fail for non-power of two values. This happens with XRootD 4.12.8.
—
Reply to this email directly, view it on GitHub, or unsubscribe.
Triage notifications on the go with GitHub Mobile for iOS or Android.
You are receiving this because you are subscribed to this thread.
Use REPLY-ALL to reply to list
To unsubscribe from the XROOTD-DEV list, click the following link:
https://listserv.slac.stanford.edu/cgi-bin/wa?SUBED1=XROOTD-DEV&A=1