sendfile

Battle ready Nginx - an optimization guide Most setup guides for Nginx tell you the basics - apt-get a package, modify a few lines here and there, and you’ve got a web server! And, in most cases, a vanilla nginx install will work just fine for serving your website. However, if you’re REALLY trying to squeeze performance out of nginx, you’ll have to go a few steps further. In this guide, I’ll explain which settings in nginx can be fine tuned in order to optimize performance for handling a large number of clients. As a note, this isn’t a comprehensive guide for fine-tuning. It’s a breif overview

I need to use sendfile64 to copy about 16GB of files. What I have achieved so far is #include <unistd.h> #include <stdio.h> #include <string.h> #include <errno.h> #include <fcntl.h> #include <stdlib.h> #include <sys/sendfile.h> #include <sys/stat.h> int main (int argc, char** argv) { long long src; long long dest; struct stat64 stat_buf; off64_t offset = 0LL; long long rc; if (argc != 3) { fprintf(stderr, "usage: %s <source> <destination>\n", argv[0]); exit(1); } src = open64(argv[1], O_RDONLY); if (src == -1) { fprintf(stderr, "unable to open '%s': %s\n", argv[1], strerror(errno)); exit(1); }

I am writing an application server that processes images (large data). I am trying to minimize copies when sending image data back to clients. The processed images I need to send to clients are in buffers obtained from jemalloc. The ways I have thought of sending the data back to the client is: 1) Simple write call. // Allocate buffer buf. // Store image data in this buffer. write(socket, buf, len); 2) I obtain the buffer through mmap instead of jemalloc, though I presume jemalloc already creates the buffer using mmap. I then make a simple call to write. buf = mmap(file, len); // Imagine

sendfile() copies data between two file descripters within kernel space. Somewhere I saw if you are writing a web server in C in linux you should use send() and recv() instead of using write() and read(). So is the send() use the kernel space as well? Whatever I use for sending - sendfile() or send() - on the client side I'll be using recv() right? On the flip side, man page says: "The only difference between send() and write(2) is the presence of flags. With a zero flags argument, send() is equivalent to write(2)." If fd is a socket file descriptor, then these system calls are identical: send