emacs find-file extremely slow over sshfs+vpn

emacs find-file extremely slow over sshfs+vpn

[Kim Barrett]

I'm trying to use emacs (29.1-1, also 28.2 and 28.1-4) on MacOS to edit files
on a remote machine via VPN and sshfs. (Mac-compatible emacs obtained from
https://emacsformacosx.com/builds.) Using emacs to read or write such files
takes a very long time, like 2-3 minutes. These are not large files. Obviously
this very usable.

It seems like the VPN is connected to the problem, since I don't see such a
delay when reading and writing files accessed via sshfs on a remote machine
that doesn't need VPN for access.

The network performance over VPN isn't amazing, but by itself it's nowhere
near bad enough to account for what I'm seeing with emacs. And I don't see
anything like that slowdown with other applications (including Aquamacs, a mac
port of emacs 25).

Searching the web finds various similar sounding complaints of various
vintages, but I'm not finding anything that matches what I'm seeing and has a
solution.

Any suggestions? I'd really like to switch to a recent version of emacs (I've
been using Aquamacs, but it's been stuck on emacs 25 for a long time). But
this problem makes that impossible for one of my main uses.

Re: emacs find-file extremely slow over sshfs+vpn

[Michael Albinus]

Kim Barrett <kab@conundrums.ca> writes:

Hi Kim,

> I'm trying to use emacs (29.1-1, also 28.2 and 28.1-4) on MacOS to edit files
> on a remote machine via VPN and sshfs. (Mac-compatible emacs obtained from
> https://emacsformacosx.com/builds.) Using emacs to read or write such files
> takes a very long time, like 2-3 minutes. These are not large files. Obviously
> this very usable.
>
> It seems like the VPN is connected to the problem, since I don't see such a
> delay when reading and writing files accessed via sshfs on a remote machine
> that doesn't need VPN for access.
>
> The network performance over VPN isn't amazing, but by itself it's nowhere
> near bad enough to account for what I'm seeing with emacs. And I don't see
> anything like that slowdown with other applications (including Aquamacs, a mac
> port of emacs 25).
>
> Searching the web finds various similar sounding complaints of various
> vintages, but I'm not finding anything that matches what I'm seeing and has a
> solution.
>
> Any suggestions? I'd really like to switch to a recent version of emacs (I've
> been using Aquamacs, but it's been stuck on emacs 25 for a long time). But
> this problem makes that impossible for one of my main uses.

In my experience, it matters to set proper cache values for sshfs. Read
the man page.

Alternatively, you could try Tramp for accessing your remote files via
its "ssh" method. Read the Tramp manual.

Best regards, Michael.

Re: emacs find-file extremely slow over sshfs+vpn

[Kim Barrett]

> On Sep 4, 2023, at 6:20 AM, Michael Albinus <michael.albinus@gmx.de> wrote:
> 
> Kim Barrett <kab@conundrums.ca> writes:
> 
> Hi Kim,
> 
>> I'm trying to use emacs (29.1-1, also 28.2 and 28.1-4) on MacOS to edit files
>> on a remote machine via VPN and sshfs. (Mac-compatible emacs obtained from
>> https://emacsformacosx.com/builds.) Using emacs to read or write such files
>> takes a very long time, like 2-3 minutes. These are not large files. Obviously
>> this very usable.
>> 
>> It seems like the VPN is connected to the problem, since I don't see such a
>> delay when reading and writing files accessed via sshfs on a remote machine
>> that doesn't need VPN for access.
>> 
>> The network performance over VPN isn't amazing, but by itself it's nowhere
>> near bad enough to account for what I'm seeing with emacs. And I don't see
>> anything like that slowdown with other applications (including Aquamacs, a mac
>> port of emacs 25).
>> 
>> Searching the web finds various similar sounding complaints of various
>> vintages, but I'm not finding anything that matches what I'm seeing and has a
>> solution.
>> 
>> Any suggestions? I'd really like to switch to a recent version of emacs (I've
>> been using Aquamacs, but it's been stuck on emacs 25 for a long time). But
>> this problem makes that impossible for one of my main uses.
> 
> In my experience, it matters to set proper cache values for sshfs. Read
> the man page.

Playing with caching options seems to me unlikely to fix my problem, since I
only see it with emacs, not with anything else (including Aquamacs, a MacOS
port of emacs 25). Emacs seems to be doing "something" when used over my
sshfs+vpn configuration, but I've no idea what or how to find out.

I spent some time fiddling with cache options anyway, and didn't detect any
improvements.

> Alternatively, you could try Tramp for accessing your remote files via
> its "ssh" method. Read the Tramp manual.
> 
> Best regards, Michael.