CS2 clock sync: the cl_clock_ commands, the recvmargin settings, and the cvars that are gone

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Quick summary

• CS2 has a clock sync system that lines the client's clock up with the server's, and it is built from a family of cl_clock_ commands.
• cl_clock_buffer_ticks is described in the dump as a replacement for cl_interp_ratio and cl_interp.
• Most of the clock commands carry the developmentonly flag, so they are not intended for normal matches.
• cl_clock_correction is labelled cheat, and cl_clockdrift_max_ticks and cl_clock_recvmargin_spew_interval are the two that carry a release flag.
• cl_interp_ratio, cl_interp_all, cl_interp_npcs and cl_smoothtime are still listed in the current dump.
• Every description below is taken from Valve's DumpSource2 convars.txt, mirrored by SteamTracking.

The clock sync commands

• cl_clock_correction, default true, flagged cheat. Enables or disables clock correction on the client.
• cl_clock_buffer_ticks, default 0, flagged developmentonly. Clock sync maintains an additional margin of this many ticks. The dump calls it a replacement for cl_interp_ratio and cl_interp, and says the value is added to cl_clock_recvmargin_desired.
• cl_clock_buffer_ticks_spectator, default 2, flagged developmentonly. An extra margin in ticks applied while spectating.
• cl_clock_recvmargin_desired, default 5, flagged developmentonly. Clock sync tries to hold this many milliseconds of margin between tick arrival and polling the network. The effective value is this number plus the time implied by cl_clock_buffer_ticks.
• cl_clock_recvmargin_window, default 4, flagged developmentonly. Clock sync looks at the past this many seconds.
• cl_clock_recvmargin_timeconstant_slowdown, default 0.3, flagged developmentonly. Clock sync removes 63.2 percent of the error in this many seconds when it slows down.
• cl_clock_recvmargin_timeconstant_speedup, default 0.6, flagged developmentonly. The same, when it speeds up.
• cl_clock_recvmargin_adjust_limit_slowdown, default 93, range 66 to 100, flagged developmentonly. Clock sync will not slow time down by more than this percentage.
• cl_clock_recvmargin_adjust_limit_speedup, default 106, range 100 to 150, flagged developmentonly. Clock sync will not speed time up by more than this percentage.
• cl_clock_recvmargin_spew_interval, default 0, flagged release. The dump gives no description for it.
• cl_clockdrift_max_ticks, default 3, range 0 or more, flagged hidden and release. The most the clock may drift before the client snaps it to the server's.
• cl_clockdbg, default false, flagged developmentonly and defensive. The dump gives no description for it.

Interpolation commands still in the dump

• cl_interp_ratio, default 2, range 0 to 19, flagged clientdll and userinfo. Sets the number of client simulation interpolation ticks.
• cl_interp_all, default false. Disables interpolation list optimizations.
• cl_interp_npcs, default 0. Interpolates NPC positions starting this many seconds in the past, or the value implied by cl_interp_ratio if that is greater.
• cl_interp_animationvars, default true. Interpolates animation variables when the interpolation interval is longer than the simulation interval.
• cl_interp_simulationvars, default true. Interpolates simulation variables under the same condition.
• cl_interp_hermite, default true, flagged clientdll and cheat. Setting it to zero disables hermite interpolation.
• cl_interp_parallel, default false. Runs interpolation in parallel for entities with no children.
• cl_interp_ag2_for_non_ag2_entities, default true.
• cl_smoothtime, default 0.2, range 0.01 to 2, flagged developmentonly. Smooths the client's view after a prediction error over this many seconds.
• cl_resend, default 0.5, range 0.1 to 2, flagged release. The delay in seconds before the client resends a connect attempt.

Commands that are not in the dump

Searching the current convars.txt for cl_interp, cl_updaterate and cl_cmdrate returns nothing. Those three are Source 1 and CS:GO commands. The clock sync family is what the dump points to instead, so an old config that sets them will have those lines ignored.

Reading the flags

Every entry in the dump carries a flag list in brackets. Most of the clock commands are marked developmentonly. cl_clock_correction is marked cheat. cl_clockdrift_max_ticks and cl_clock_recvmargin_spew_interval are marked release. The dump prints the flags but does not define them, so treat them as a guide to which commands are meant to be usable rather than a guarantee.

FAQ

Q: What does cl_clock_recvmargin_desired actually set?
A: Not the whole margin. The dump says the effective value is cl_clock_recvmargin_desired plus the time implied by cl_clock_buffer_ticks.

Q: Why is cl_clock_correction flagged cheat?
A: The dump labels it cheat. That flag marks commands that need cheats enabled.

Q: Is cl_interp gone from CS2?
A: It is not in the current dump. cl_interp_ratio is, and cl_clock_buffer_ticks is described as its replacement.

Q: Should I raise cl_clock_buffer_ticks for a bad connection?
A: The dump describes it as a replacement for cl_interp_ratio and cl_interp and marks it developmentonly. It is not a setting to carry over from an old config.

Sources
Valve DumpSource2 convars.txt, mirrored by SteamTracking
CS2 convar explorer for the same dump