On Thu, Aug 11, 2022 at 09:50:54AM +0700, John Naylor wrote:
> I was waiting for all the Windows animals to report in, and it looks
> like they have, so I've pushed 0002. Thanks for picking this topic up
> again!
Thanks for reviewing and committing.
--
Nathan Bossart
Amazon Web Services: https:/
On Thu, Aug 11, 2022 at 4:46 AM Nathan Bossart wrote:
>
> On Wed, Aug 10, 2022 at 10:50:02AM +0700, John Naylor wrote:
> > LGTM, let's see what the buildfarm thinks of 0001.
>
> Thanks! I haven't noticed any related buildfarm failures yet.
I was waiting for all the Windows animals to report in,
On Wed, Aug 10, 2022 at 10:50:02AM +0700, John Naylor wrote:
> LGTM, let's see what the buildfarm thinks of 0001.
Thanks! I haven't noticed any related buildfarm failures yet.
--
Nathan Bossart
Amazon Web Services: https://aws.amazon.com
On Wed, Aug 10, 2022 at 7:13 AM Nathan Bossart wrote:
>
> On Tue, Aug 09, 2022 at 01:00:37PM -0700, Nathan Bossart wrote:
> > Your adjustments in 0002 seem reasonable to me. I think it makes sense to
> > ensure there is test coverage for pg_lfind32(), but I don't know if that
> > syscache code is
On Wed, Aug 10, 2022 at 5:00 AM Nathan Bossart wrote:
>
> On Tue, Aug 09, 2022 at 01:21:41PM +0700, John Naylor wrote:
> > I decided I wasn't quite comfortable changing snapshot handling
> > without further guarantees. To this end, 0002 in the attached v11 is
> > an addendum that adds assert chec
On Tue, Aug 09, 2022 at 01:00:37PM -0700, Nathan Bossart wrote:
> Your adjustments in 0002 seem reasonable to me. I think it makes sense to
> ensure there is test coverage for pg_lfind32(), but I don't know if that
> syscache code is the right choice. For non-USE_SSE2 builds, it might make
> thes
On Tue, Aug 09, 2022 at 01:21:41PM +0700, John Naylor wrote:
> I decided I wasn't quite comfortable changing snapshot handling
> without further guarantees. To this end, 0002 in the attached v11 is
> an addendum that adds assert checking (also pgindent and some
> comment-smithing). As I suspected,
On Tue, Aug 9, 2022 at 10:51 AM Nathan Bossart wrote:
> Fixed in v10.
I decided I wasn't quite comfortable changing snapshot handling
without further guarantees. To this end, 0002 in the attached v11 is
an addendum that adds assert checking (also pgindent and some
comment-smithing). As I suspect
Nathan Bossart writes:
> On Tue, Aug 09, 2022 at 09:40:15AM +0530, Bharath Rupireddy wrote:
>> Isn't it a good idea to capture the above two points as comments in
>> port/pg_lfind.h just to not lose track of it? I know these are present
>> in the hackers thread, but having them in the form of comm
On Tue, Aug 09, 2022 at 09:40:15AM +0530, Bharath Rupireddy wrote:
> Isn't it a good idea to capture the above two points as comments in
> port/pg_lfind.h just to not lose track of it? I know these are present
> in the hackers thread, but having them in the form of comments helps
> developers who a
On Tue, Aug 9, 2022 at 4:37 AM Nathan Bossart wrote:
>
> On Mon, Aug 08, 2022 at 12:56:28PM +0530, Bharath Rupireddy wrote:
> > 1) pg_lfind32 - why just uint32? If it's not possible to define
> > functions for char, unsigned char, int16, uint16, int32, int64, uint64
> > and so on, can we add a few
On Tue, Aug 09, 2022 at 10:57:44AM +0900, Masahiko Sawada wrote:
> The patch looks good to me. One minor point is:
Thanks for taking a look.
> + * IDENTIFICATION
> + * src/port/pg_lfind.h
>
> The path doesn't match to the actual file path, src/include/port/pg_lfind.h.
Fixed in v10.
--
Natha
On Tue, Aug 9, 2022 at 7:33 AM Nathan Bossart wrote:
>
> On Mon, Aug 08, 2022 at 01:46:48PM +0700, John Naylor wrote:
> > Okay, I think it's basically in good shape. Since it should be a bit
> > faster than a couple versions ago, would you be up for retesting with
> > the original test having 8 to
On Mon, Aug 08, 2022 at 12:56:28PM +0530, Bharath Rupireddy wrote:
> 1) pg_lfind32 - why just uint32? If it's not possible to define
> functions for char, unsigned char, int16, uint16, int32, int64, uint64
> and so on, can we add a few comments around that? Also, the comments
> can talk about if th
On Mon, Aug 08, 2022 at 01:46:48PM +0700, John Naylor wrote:
> Okay, I think it's basically in good shape. Since it should be a bit
> faster than a couple versions ago, would you be up for retesting with
> the original test having 8 to 512 writers?
Sure thing. The results are similar. As before,
On Mon, Aug 8, 2022 at 2:30 PM John Naylor wrote:
>
> On Mon, Aug 8, 2022 at 2:26 PM Bharath Rupireddy
> wrote:
>
> > 3) Can pg_lfind32 return the index of the key found, for instance to
> > use it for setting/resetting the found element in the array?
>
> That was just discussed. It's slightly f
On Mon, Aug 8, 2022 at 2:26 PM Bharath Rupireddy
wrote:
>
>
> 1) pg_lfind32 - why just uint32? If it's not possible to define
> functions for char, unsigned char, int16, uint16, int32, int64, uint64
> and so on, can we add a few comments around that? Also, the comments
Future work, as far as I'm
On Mon, Aug 8, 2022 at 12:17 PM John Naylor
wrote:
>
> On Sun, Aug 7, 2022 at 4:25 AM Nathan Bossart
> wrote:
> >
> > [v8]
>
> Okay, I think it's basically in good shape. Since it should be a bit
> faster than a couple versions ago, would you be up for retesting with
> the original test having 8
On Sun, Aug 7, 2022 at 4:25 AM Nathan Bossart wrote:
>
> [v8]
Okay, I think it's basically in good shape. Since it should be a bit
faster than a couple versions ago, would you be up for retesting with
the original test having 8 to 512 writers? And also add the const
markers we discussed upthread?
On Sat, Aug 06, 2022 at 11:13:26AM -0700, Nathan Bossart wrote:
> On Fri, Aug 05, 2022 at 03:04:34PM -0700, Andres Freund wrote:
>> But mainly I'd expect to find a difference if the SIMD code were optimized a
>> further on the basis of not needing to return the offset. E.g. by
>> replacing _mm_pack
On Fri, Aug 05, 2022 at 03:04:34PM -0700, Andres Freund wrote:
> But mainly I'd expect to find a difference if the SIMD code were optimized a
> further on the basis of not needing to return the offset. E.g. by
> replacing _mm_packs_epi32 with _mm_or_si128, that's cheaper.
I haven't been able to fi
Hi,
On 2022-08-05 13:25:10 -0700, Nathan Bossart wrote:
> I went ahead and renamed it to pg_lfind32() and switched it back to
> returning the pointer. That felt the cleanest from the naming perspective,
> but as Andres noted, it might not be as fast as just looking for the
> presence of the eleme
On Fri, Aug 05, 2022 at 11:02:15AM +0700, John Naylor wrote:
> That is a good point. Maybe potential helpers in simd.h should only deal
> specifically with vector registers, with it's users providing C fallbacks.
> I don't have any good ideas of where to put the new function, though.
I moved it to
On Fri, Aug 5, 2022 at 5:15 AM Nathan Bossart
wrote:
>
> On Thu, Aug 04, 2022 at 02:58:14PM +0700, John Naylor wrote:
> > Were you considering adding the new function to simd.h now that that's
> > committed? It's a bit up in the air what should go in there, but this
new
> > function is low-level a
On Thu, Aug 04, 2022 at 02:58:14PM +0700, John Naylor wrote:
> Were you considering adding the new function to simd.h now that that's
> committed? It's a bit up in the air what should go in there, but this new
> function is low-level and generic enough to be a candidate...
I don't have a strong op
On Thu, Aug 4, 2022 at 3:25 AM Nathan Bossart
wrote:
> Here is a new patch set without the annotation.
Were you considering adding the new function to simd.h now that that's
committed? It's a bit up in the air what should go in there, but this new
function is low-level and generic enough to be a
On Wed, Aug 03, 2022 at 11:06:58AM -0700, Andres Freund wrote:
> On 2022-08-02 16:43:57 -0700, Nathan Bossart wrote:
>> >> +#ifdef USE_SSE2
>> >> +pg_attribute_no_sanitize_alignment()
>> >> +#endif
>> >
>> > What's the deal with this annotation? Needs a comment.
>>
>> Will do. c.h suggests that
Hi,
On 2022-08-02 16:43:57 -0700, Nathan Bossart wrote:
> >> +/*
> >> + * pg_linearsearch_uint32
> >> + *
> >> + * Returns the address of the first element in 'base' that equals 'key',
> >> or
> >> + * NULL if no match is found.
> >> + */
> >> +#ifdef USE_SSE2
> >> +pg_attribute_no_sanitize_align
Here is a new patch set. 0001 is the currently-proposed patch from the
other thread [0] for determining SSE2 support. 0002 introduces the
optimized linear search function. And 0003 makes use of the new function
for the [sub]xip lookups in XidInMVCCSnapshot().
[0]
https://postgr.es/m/CAFBsxsGkt
On Wed, Aug 3, 2022 at 6:43 AM Nathan Bossart
wrote:
> Just under half of the callers in 0002 require the offset, but I don't
know
> if any of those are worth optimizing in the first place. I'll change it
> for now. It's easy enough to add it back in the future if required.
Yeah, some of those
On Tue, Aug 02, 2022 at 03:55:39PM -0700, Andres Freund wrote:
> FWIW, I'd split the introduction of the helper and the use of it in snapmgr
> into separate patches.
Will do.
> On 2022-08-02 15:13:01 -0700, Nathan Bossart wrote:
>> diff --git a/src/include/c.h b/src/include/c.h
>> index d35405f19
Hi,
FWIW, I'd split the introduction of the helper and the use of it in snapmgr
into separate patches.
On 2022-08-02 15:13:01 -0700, Nathan Bossart wrote:
> diff --git a/src/include/c.h b/src/include/c.h
> index d35405f191..2c1a47bc28 100644
> --- a/src/include/c.h
> +++ b/src/include/c.h
> @@ -
On Fri, Jul 29, 2022 at 10:38:11PM -0700, Nathan Bossart wrote:
> On Sat, Jul 30, 2022 at 12:02:02PM +0700, John Naylor wrote:
>> I'll be the first to say it's not committable and needs some thought. Since
>> there are several recently proposed patches that take advantage of SSE2, it
>> seems time
On Sat, Jul 30, 2022 at 12:02:02PM +0700, John Naylor wrote:
> On Fri, Jul 29, 2022 at 4:34 AM Nathan Bossart
> wrote:
>> * I borrowed USE_SSE2 from one of John Naylor's patches [0]. I'm not
> sure
>>whether this is committable,
>
> I'll be the first to say it's not committable and needs so
On Fri, Jul 29, 2022 at 4:34 AM Nathan Bossart
wrote:
> * I briefly looked into seeing whether auto-vectorization was viable and
>concluded it was not for these loops.
>
> * I borrowed USE_SSE2 from one of John Naylor's patches [0]. I'm not
sure
>whether this is committable,
I'll be th
On Tue, Jul 26, 2022 at 11:19:06AM -0700, Andres Freund wrote:
> On 2022-07-25 12:04:19 -0700, Nathan Bossart wrote:
>> From the discussion thus far, it seems there is interest in optimizing
>> [sub]xip lookups, so I'd like to spend some time moving it forward. I
>> think the biggest open question
On 2022-07-25 12:04:19 -0700, Nathan Bossart wrote:
> On Sat, Jul 16, 2022 at 08:59:57PM -0700, Nathan Bossart wrote:
> > On Fri, Jul 15, 2022 at 01:08:57PM -0700, Andres Freund wrote:
> >> I wonder if we additionally / alternatively could use a faster method of
> >> searching the array linearly, e
> On Jul 26, 2022, at 03:04, Nathan Bossart wrote:
>>
> From the discussion thus far, it seems there is interest in optimizing
> [sub]xip lookups, so I'd like to spend some time moving it forward. I
> think the biggest open question is which approach to take. Both the SIMD
> and hash table
On Sat, Jul 16, 2022 at 08:59:57PM -0700, Nathan Bossart wrote:
> On Fri, Jul 15, 2022 at 01:08:57PM -0700, Andres Freund wrote:
>> I wonder if we additionally / alternatively could use a faster method of
>> searching the array linearly, e.g. using SIMD.
>
> I looked into using SIMD. The patch is
Got it, thanks.
Regards,
Zhang Mingli
> On Jul 25, 2022, at 12:08, Nathan Bossart wrote:
>
> On Sun, Jul 24, 2022 at 12:48:25PM +0800, Zhang Mingli wrote:
>> If snaphost->suboverflowed is false then the subxcnt must be less than
>> PGPROC_MAX_CACHED_SUBXIDS which is 64 now.
>>
>> And we
On Sun, Jul 24, 2022 at 12:48:25PM +0800, Zhang Mingli wrote:
> If snaphost->suboverflowed is false then the subxcnt must be less than
> PGPROC_MAX_CACHED_SUBXIDS which is 64 now.
>
> And we won’t use hash if the xcnt is less than XIP_HASH_MIN_ELEMENTS which is
> 128 currently during discussion
В Ср, 13/07/2022 в 10:09 -0700, Nathan Bossart пишет:
> Hi hackers,
>
> A few years ago, there was a proposal to create hash tables for long
> [sub]xip arrays in snapshots [0], but the thread seems to have fizzled out.
> I was curious whether this idea still showed measurable benefits, so I
> reva
Hi, all
>
> if (!snapshot->suboverflowed)
> {
> /* we have full data, so search subxip */
> - int32 j;
> -
> - for (j = 0; j < snapshot->subxcnt; j++)
> - {
> -
Hi Andres,
Thanks for taking a look.
On Fri, Jul 15, 2022 at 01:08:57PM -0700, Andres Freund wrote:
> Hm. Are there any contexts where we'd not want the potential for failing due
> to OOM?
I'm not sure about this one.
> I wonder if we additionally / alternatively could use a faster method of
>
Hi,
Sounds worth pursuing.
On 2022-07-13 10:09:50 -0700, Nathan Bossart wrote:
> The attached patch has some key differences from the previous proposal.
> For example, the new patch uses simplehash instead of open-coding a new
> hash table.
+1
> The attached patch waits until a lookup of [sub]x
Hi Bharath,
Thanks for taking a look.
On Thu, Jul 14, 2022 at 03:10:56PM +0530, Bharath Rupireddy wrote:
> Aren't these snapshot arrays always sorted? I see the following code:
>
> /* sort so we can bsearch() */
> qsort(snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator);
>
> /
On Wed, Jul 13, 2022 at 10:40 PM Nathan Bossart
wrote:
>
> Hi hackers,
>
> A few years ago, there was a proposal to create hash tables for long
> [sub]xip arrays in snapshots [0], but the thread seems to have fizzled out.
> I was curious whether this idea still showed measurable benefits, so I
> r
Hi hackers,
A few years ago, there was a proposal to create hash tables for long
[sub]xip arrays in snapshots [0], but the thread seems to have fizzled out.
I was curious whether this idea still showed measurable benefits, so I
revamped the patch and ran the same test as before [1]. Here are the
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