netdev - Re: net: more accurate skb truesize

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <1334050698.3126.30.camel@edumazet-glaptop>
Date:	Tue, 10 Apr 2012 11:38:18 +0200
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	monstr@...str.eu
Cc:	netdev@...r.kernel.org,
	John Williams <john.williams@...alogix.com>,
	David Miller <davem@...emloft.net>
Subject: Re: net: more accurate skb truesize - regression on Microblaze

On Tue, 2012-04-10 at 11:29 +0200, Michal Simek wrote:
> On 04/10/2012 11:24 AM, Eric Dumazet wrote:
> > On Tue, 2012-04-10 at 11:11 +0200, Michal Simek wrote:
> >
> >> ~ # cat /proc/sys/net/ipv4/tcp_rmem
> >> 4096    87380   130048
> >
> > Are they default values, or tuned by admin ?
> >
> > 130048 bytes isnt enough to let TCP open its rcv window.
> 
> yep. Default value after powerup. What's wrong with that?
> 
> Michal
> 

I guess your tcp performance is driven by these numbers mostly.

receive window wont grow above 64K in these case. a tcpdump could
confirm the issue.

Do you have 130000 pages of memory ?

Seems the net/ipv4/tcp.c code is wrong (or the comment is wrong)

Since its not 1/128 but 1/1024 ....


        /* Set per-socket limits to no more than 1/128 the pressure threshold */
        limit = nr_free_buffer_pages() << (PAGE_SHIFT - 10);
        limit = max(limit, 128UL);
        max_share = min(4UL*1024*1024, limit);

        sysctl_tcp_wmem[0] = SK_MEM_QUANTUM;
        sysctl_tcp_wmem[1] = 16*1024;
        sysctl_tcp_wmem[2] = max(64*1024, max_share);

        sysctl_tcp_rmem[0] = SK_MEM_QUANTUM;
        sysctl_tcp_rmem[1] = 87380;
        sysctl_tcp_rmem[2] = max(87380, max_share);


--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html