Date: Thu, 29 Nov 2018 18:18:38 -0800
From: ianswett <notifications@github.com>
Reply-To: quicwg/base-drafts
 <reply+0166e4ab8bb4b434e82ea65442065a1bb1e381b57193c3a792cf0000000118185ffe92a169ce16f4226e@reply.github.com>
To: quicwg/base-drafts <base-drafts@noreply.github.com>
Cc: Subscribed <subscribed@noreply.github.com>
Message-ID: <quicwg/base-drafts/issues/2060/443066647@github.com>
In-Reply-To: <quicwg/base-drafts/issues/2060@github.com>
References: <quicwg/base-drafts/issues/2060@github.com>
Subject: Re: [quicwg/base-drafts] compensation of ack_delay is fragile against
 errors (#2060)
Mime-Version: 1.0
Content-Type: multipart/alternative;
 boundary="--==_mimepart_5c009dfed98ef_10c73faa1e0d45b4303413";
 charset=UTF-8
Content-Transfer-Encoding: 7bit
Precedence: list
Archived-At: <https://mailarchive.ietf.org/arch/msg/quic-issues/vHcFCv5Q7noRui3KPv4pwn-fpSc>


----==_mimepart_5c009dfed98ef_10c73faa1e0d45b4303413
Content-Type: text/plain;
 charset=UTF-8
Content-Transfer-Encoding: 7bit

In regards to min(ack_delay, max_ack_delay), it's critical to consider what srtt is used for, which is loss detection and timers(TLP and RTO).

If there is a high rate of ACK loss or if the peer's alarms are persistently waking up late, then the SRTT and/or RTTVar will increase, thereby increasing these timers.  If this happens very infrequently, then the EWMA will forget them relatively quickly.  I think that seems appropriate?

To think of the pathological case, what if a peer communicates a max_ack_delay of 0?  I think it's important the rest of the recovery machinery still functions correctly in that case.

-- 
You are receiving this because you are subscribed to this thread.
Reply to this email directly or view it on GitHub:
https://github.com/quicwg/base-drafts/issues/2060#issuecomment-443066647
----==_mimepart_5c009dfed98ef_10c73faa1e0d45b4303413
Content-Type: text/html;
 charset=UTF-8
Content-Transfer-Encoding: quoted-printable

<p>In regards to min(ack_delay, max_ack_delay), it's critical to consider=
 what srtt is used for, which is loss detection and timers(TLP and RTO).<=
/p>
<p>If there is a high rate of ACK loss or if the peer's alarms are persis=
tently waking up late, then the SRTT and/or RTTVar will increase, thereby=
 increasing these timers.  If this happens very infrequently, then the EW=
MA will forget them relatively quickly.  I think that seems appropriate?<=
/p>
<p>To think of the pathological case, what if a peer communicates a max_a=
ck_delay of 0?  I think it's important the rest of the recovery machinery=
 still functions correctly in that case.</p>

<p style=3D"font-size:small;-webkit-text-size-adjust:none;color:#666;">&m=
dash;<br />You are receiving this because you are subscribed to this thre=
ad.<br />Reply to this email directly, <a href=3D"https://github.com/quic=
wg/base-drafts/issues/2060#issuecomment-443066647">view it on GitHub</a>,=
 or <a href=3D"https://github.com/notifications/unsubscribe-auth/AWbkq9kF=
-3HicIhSyOEchIOjJCpJjy_Tks5u0JV-gaJpZM4Y22J5">mute the thread</a>.<img sr=
c=3D"https://github.com/notifications/beacon/AWbkq1ayEjOBbxxTTjm1kEuaztNy=
-Kllks5u0JV-gaJpZM4Y22J5.gif" height=3D"1" width=3D"1" alt=3D"" /></p>
<script type=3D"application/json" data-scope=3D"inboxmarkup">{"api_versio=
n":"1.0","publisher":{"api_key":"05dde50f1d1a384dd78767c55493e4bb","name"=
:"GitHub"},"entity":{"external_key":"github/quicwg/base-drafts","title":"=
quicwg/base-drafts","subtitle":"GitHub repository","main_image_url":"http=
s://assets-cdn.github.com/images/email/message_cards/header.png","avatar_=
image_url":"https://assets-cdn.github.com/images/email/message_cards/avat=
ar.png","action":{"name":"Open in GitHub","url":"https://github.com/quicw=
g/base-drafts"}},"updates":{"snippets":[{"icon":"PERSON","message":"@ians=
wett in #2060: In regards to min(ack_delay, max_ack_delay), it's critical=
 to consider what srtt is used for, which is loss detection and timers(TL=
P and RTO).\r\n\r\nIf there is a high rate of ACK loss or if the peer's a=
larms are persistently waking up late, then the SRTT and/or RTTVar will i=
ncrease, thereby increasing these timers.  If this happens very infrequen=
tly, then the EWMA will forget them relatively quickly.  I think that see=
ms appropriate?\r\n\r\nTo think of the pathological case, what if a peer =
communicates a max_ack_delay of 0?  I think it's important the rest of th=
e recovery machinery still functions correctly in that case."}],"action":=
{"name":"View Issue","url":"https://github.com/quicwg/base-drafts/issues/=
2060#issuecomment-443066647"}}}</script>
<script type=3D"application/ld+json">[
{
"@context": "http://schema.org",
"@type": "EmailMessage",
"potentialAction": {
"@type": "ViewAction",
"target": "https://github.com/quicwg/base-drafts/issues/2060#issuecomment=
-443066647",
"url": "https://github.com/quicwg/base-drafts/issues/2060#issuecomment-44=
3066647",
"name": "View Issue"
},
"description": "View this Issue on GitHub",
"publisher": {
"@type": "Organization",
"name": "GitHub",
"url": "https://github.com"
}
},
{
"@type": "MessageCard",
"@context": "http://schema.org/extensions",
"hideOriginalBody": "false",
"originator": "AF6C5A86-E920-430C-9C59-A73278B5EFEB",
"title": "Re: [quicwg/base-drafts] compensation of ack_delay is fragile a=
gainst errors (#2060)",
"sections": [
{
"text": "",
"activityTitle": "**ianswett**",
"activityImage": "https://assets-cdn.github.com/images/email/message_card=
s/avatar.png",
"activitySubtitle": "@ianswett",
"facts": [

]
}
],
"potentialAction": [
{
"name": "Add a comment",
"@type": "ActionCard",
"inputs": [
{
"isMultiLine": true,
"@type": "TextInput",
"id": "IssueComment",
"isRequired": false
}
],
"actions": [
{
"name": "Comment",
"@type": "HttpPOST",
"target": "https://api.github.com",
"body": "{\n\"commandName\": \"IssueComment\",\n\"repositoryFullName\": \=
"quicwg/base-drafts\",\n\"issueId\": 2060,\n\"IssueComment\": \"{{IssueCo=
mment.value}}\"\n}"
}
]
},
{
"name": "Close issue",
"@type": "HttpPOST",
"target": "https://api.github.com",
"body": "{\n\"commandName\": \"IssueClose\",\n\"repositoryFullName\": \"q=
uicwg/base-drafts\",\n\"issueId\": 2060\n}"
},
{
"targets": [
{
"os": "default",
"uri": "https://github.com/quicwg/base-drafts/issues/2060#issuecomment-44=
3066647"
}
],
"@type": "OpenUri",
"name": "View on GitHub"
},
{
"name": "Unsubscribe",
"@type": "HttpPOST",
"target": "https://api.github.com",
"body": "{\n\"commandName\": \"MuteNotification\",\n\"threadId\": 4170307=
77\n}"
}
],
"themeColor": "26292E"
}
]</script>=

----==_mimepart_5c009dfed98ef_10c73faa1e0d45b4303413--