I’d like to investigate various ‘block size’ variations in TPC-HTTP (especially writes); 
(by which I mean the size of the write that is passed to the server from the proxy, I hope that makes sense … ) 

By default, I think writes are written at 1MiB boundaries.
From the code, I’m hoping I could make the following changes (see diff below), but it’s not clear if there are some subtle effects to be aware of, or if I’ve missed some obvious problem (i.e. like making sure they are at least written at sensible sizes). 

The motivation is that I’m observing slow transfers in http-tpc (relative to root for example), and would like to test the effect of ‘block size’ changes, for which we are quite sensitive to.
Any thoughts would be appreciated.

Thanks in advance,

(Based on 5.3.0-1) 

diff --git a/src/XrdTpc/XrdTpcStream.cc b/src/XrdTpc/XrdTpcStream.cc
index 76c7d6e..c2ff92d 100644
--- a/src/XrdTpc/XrdTpcStream.cc
+++ b/src/XrdTpc/XrdTpcStream.cc
@@ -80,7 +80,7 @@ Stream::Write(off_t offset, const char *buf, size_t size, bool force)
     // If this is write is appending to the stream and
     // MB-aligned, then we write it to disk; otherwise, the
     // data will be buffered.
-    if (offset == m_offset && (force || (size && !(size % (1024*1024))))) {
+    if (offset == m_offset && (force || (size && !(size % (16*1024*1024))))) {
         retval = WriteImpl(offset, buf, size);
         bytes_accepted = retval;
             // On failure, we don't care about flushing buffers from memory —

diff --git a/src/XrdTpc/XrdTpcTPC.cc b/src/XrdTpc/XrdTpcTPC.cc
index d800dfa..fff4a1e 100644
--- a/src/XrdTpc/XrdTpcTPC.cc
+++ b/src/XrdTpc/XrdTpcTPC.cc
@@ -26,7 +26,7 @@ using namespace TPC;
 uint64_t TPCHandler::m_monid{0};
 int TPCHandler::m_marker_period = 5;
 size_t TPCHandler::m_block_size = 16*1024*1024;
-size_t TPCHandler::m_small_block_size = 1*1024*1024;
+size_t TPCHandler::m_small_block_size = 16*1024*1024;
 XrdSysMutex TPCHandler::m_monid_mutex;


 XrdVERSIONINFO(XrdHttpGetExtHandler, HttpTPC);

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