Mercurial > hg
view mercurial/compat.h @ 30212:260af19891f2
changegroup: increase write buffer size to 128k
By default, Python defers to the operating system for choosing the
default buffer size on opened files. On my Linux machine, the default
is 4k, which is really small for 2016.
This patch bumps the write buffer size when writing
changegroups/bundles to 128k. This matches the 128k read buffer
we already use on revlogs.
It's worth noting that this only impacts when writing to an explicit
file (such as during `hg bundle`). Buffers when writing to bundle
files via the repo vfs or to a temporary file are not impacted.
When producing a none-v2 bundle file of the mozilla-unified repository,
this change caused the number of write() system calls to drop from
952,449 to 29,788. After this change, the most frequent system
calls are fstat(), read(), lseek(), and open(). There were
2,523,672 system calls after this patch (so a net decrease of
~950k is statistically significant).
This change shows no performance change on my system. But I have a
high-end system with a fast SSD. It is quite possible this change
will have a significant impact on network file systems, where
extra network round trips due to excessive I/O system calls could
introduce significant latency.
author | Gregory Szorc <gregory.szorc@gmail.com> |
---|---|
date | Sun, 16 Oct 2016 13:35:23 -0700 |
parents | 7b22599dcb85 |
children | f4433f2713d0 |
line wrap: on
line source
#ifndef _HG_COMPAT_H_ #define _HG_COMPAT_H_ #ifdef _WIN32 #ifdef _MSC_VER /* msvc 6.0 has problems */ #define inline __inline #if defined(_WIN64) typedef __int64 ssize_t; #else typedef int ssize_t; #endif typedef signed char int8_t; typedef short int16_t; typedef long int32_t; typedef __int64 int64_t; typedef unsigned char uint8_t; typedef unsigned short uint16_t; typedef unsigned long uint32_t; typedef unsigned __int64 uint64_t; #else #include <stdint.h> #endif #else /* not windows */ #include <sys/types.h> #if defined __BEOS__ && !defined __HAIKU__ #include <ByteOrder.h> #else #include <arpa/inet.h> #endif #include <inttypes.h> #endif #if defined __hpux || defined __SUNPRO_C || defined _AIX #define inline #endif #ifdef __linux #define inline __inline #endif #endif