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From: Petr Vorel <pvorel@suse.cz>
To: ltp@lists.linux.it
Subject: [LTP] [PATCH v3 1/2] splice02: Generate input in C
Date: Fri, 16 Apr 2021 15:10:07 +0200	[thread overview]
Message-ID: <YHmMr/8QB8RByu+l@pevik> (raw)
In-Reply-To: <YHmD6Efvn/f6Eh+G@yuki>

Hi Cyril,

...
> > Maybe one more change: INT_MAX is a bit too much, it timeouts.
> > I'll use 262144 as max allowed -n (the default on intel - 2x max pipe size).

> I guess that the main problem here is that we write one character at a
> time, which means that we spend most of the time in syscall handler code
> rather than copying the data. It may work much better if we change the
> code to write 512 bytes at a time. I.e. something as:

Sounds very reasonable, thx! I'll send v4.

Kind regards,
Petr

> 	#define BUFSIZE 512

> 	char buf[BUFSIZE];

> 	memset(buf, 'a', BUFSIZE);

> 	while (to_write > 0) {
> 		size_t size = to_write > BUFSIZE ? BUFSIZE : to_write;

> 		...

> 		to_write -= written;
> 	}

      reply	other threads:[~2021-04-16 13:10 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-13  4:38 [LTP] [PATCH v3 1/2] splice02: Generate input in C Petr Vorel
2021-04-13  4:38 ` [LTP] [PATCH v3 2/2] commands: Add shell pipe test Petr Vorel
2021-04-15 13:46 ` [LTP] [PATCH v3 1/2] splice02: Generate input in C Cyril Hrubis
2021-04-15 14:11   ` Petr Vorel
2021-04-15 14:27     ` Petr Vorel
2021-04-16 12:32       ` Cyril Hrubis
2021-04-16 13:10         ` Petr Vorel [this message]

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