From: Junio C Hamano <gitster@pobox.com>
Date: Tue, 20 Aug 2013 19:37:49 GMT
Subject: Re: [PATCH v5 1/2] xread, xwrite: Limit size of IO, fixing IO of 2GB and more on Mac OS X
Message-ID: <xmqqli3w5f1u.fsf@gitster.dls.corp.google.com>
In-Reply-To: <1376981035-23284-2-git-send-email-prohaska@zib.de>

Steffen Prohaska <prohaska@zib.de> writes:

> diff --git a/wrapper.c b/wrapper.c
> index 6a015de..97e3cf7 100644
> --- a/wrapper.c
> +++ b/wrapper.c
> @@ -131,6 +131,14 @@ void *xcalloc(size_t nmemb, size_t size)
>  }
>  
>  /*
> + * Limit size of IO chunks, because huge chunks only cause pain.  OS X 64-bit
> + * buggy, returning EINVAL if len >= INT_MAX; and even in the absense of bugs,

s/buggy/is &/ perhaps?

> + * large chunks can result in bad latencies when you decide to kill the
> + * process.
> + */
> +#define MAX_IO_SIZE (8*1024*1024)
> +
> +/*
>   * xread() is the same a read(), but it automatically restarts read()
>   * operations with a recoverable error (EAGAIN and EINTR). xread()
>   * DOES NOT GUARANTEE that "len" bytes is read even if the data is available.
> @@ -138,6 +146,8 @@ void *xcalloc(size_t nmemb, size_t size)
>  ssize_t xread(int fd, void *buf, size_t len)
>  {
>  	ssize_t nr;
> +	if (len > MAX_IO_SIZE)
> +	    len = MAX_IO_SIZE;
>  	while (1) {
>  		nr = read(fd, buf, len);
>  		if ((nr < 0) && (errno == EAGAIN || errno == EINTR))
> @@ -154,6 +164,8 @@ ssize_t xread(int fd, void *buf, size_t len)
>  ssize_t xwrite(int fd, const void *buf, size_t len)
>  {
>  	ssize_t nr;
> +	if (len > MAX_IO_SIZE)
> +	    len = MAX_IO_SIZE;
>  	while (1) {
>  		nr = write(fd, buf, len);
>  		if ((nr < 0) && (errno == EAGAIN || errno == EINTR))